libltdl: remove embedded libltdl

Per open-mpi#311, Libtool v2.4.4 exposes a bug in either Libtool
and/or autoreconf (after discussions with Libtool and Autoconf
maintainers, it's not clear which) when embedding libltdl.

After some discussion in the Open MPI community, we have decided to
both remove our embedded libltdl and (mostly) treat libltdl like any
other external library:

* If --disable-dlopen is specified, it behaves as it always has:
  libltdl support is wholly disabled, and all plugins are slurped into
  their higher-level libraries.
* If --enable-dlopen is specified, configure will abort if it cannot
  find properly libltdl support.
* If neither of these are specified, configure will behave differently
  between a developer build (i.e., where a .git directory is present
  in the source tree) and non-developer build:
  * In a developer build, --enable-dlopen is assumed (i.e., configure
    will abort if libltdl support cannot be found). --disable-dlopen
    must be specified if you do not have libltdl support.
  * In a non-developer build:
    * If configure finds libltdl support, it will build dlopen support
      and build plugins as DSOs.
    * If configure does not find libltdl support, it will disable dlopen
      support and slurp plugins into higher level libraries.

The developer build behavior is because dlopen support is usually
highly valued (e.g., being able to repeatedly build individual
plugins), and libltdl-devel may not be installed by default on Linux
distros and OSX. Hence, developers may inadvertently build without
dlopen support without this special developer-build provision.

Fixes open-mpi#311.

README

@@ -8,7 +8,7 @@ Copyright (c) 2004-2008 High Performance Computing Center Stuttgart,
                         University of Stuttgart.  All rights reserved.
 Copyright (c) 2004-2007 The Regents of the University of California.
                         All rights reserved.
-Copyright (c) 2006-2014 Cisco Systems, Inc.  All rights reserved.
+Copyright (c) 2006-2015 Cisco Systems, Inc.  All rights reserved.
 Copyright (c) 2006-2011 Mellanox Technologies. All rights reserved.
 Copyright (c) 2006-2012 Oracle and/or its affiliates.  All rights reserved.
 Copyright (c) 2007      Myricom, Inc.  All rights reserved.
@@ -812,19 +812,27 @@ INSTALLATION OPTIONS
 
 --enable-dlopen
   Build all of Open MPI's components as standalone Dynamic Shared
-  Objects (DSO's) that are loaded at run-time (this is the default).
+  Objects (DSO's) that are loaded at run-time.  configure will abort
+  if proper DSO support cannot be found on the build system (i.e., the
+  GNU Libltdl library and header files).
+
   The opposite of this option, --disable-dlopen, causes two things:
 
   1. All of Open MPI's components will be built as part of Open MPI's
      normal libraries (e.g., libmpi).  
   2. Open MPI will not attempt to open any DSO's at run-time.
 
-  Note that this option does *not* imply that OMPI's libraries will be
-  built as static objects (e.g., libmpi.a).  It only specifies the
-  location of OMPI's components: standalone DSOs or folded into the
-  Open MPI libraries.  You can control whether Open MPI's libraries
-  are build as static or dynamic via --enable|disable-static and
-  --enable|disable-shared.
+  Note that --disable-dlopen does *not* imply that OMPI's libraries
+  will be built as static objects (e.g., libmpi.a).  It only specifies
+  the location of OMPI's components: standalone DSOs or folded into
+  the Open MPI libraries.  You can control whether Open MPI's
+  libraries are build as static or dynamic via --enable|disable-static
+  and --enable|disable-shared.
+
+  If neither --enable-dlopen nor --disable-dlopen are specified, Open
+  MPI will enable dlopen support if it can find proper DSO support on
+  the build system, or behave as if --disable-dlopen was specified if
+  it cannot find proper DSO support on the build system.
 
 --with-platform=FILE
   Load configure options for the build from FILE.  Options on the
@@ -1136,28 +1144,6 @@ MISCELLANEOUS SUPPORT LIBRARIES
   hwloc can discover PCI devices and locality, which can be useful for
   Open MPI in assigning message passing resources to MPI processes.
 
---with-libltdl(=value)
-  This option specifies where to find the GNU Libtool libltdl support
-  library.  The following values are permitted:
-
-    internal:    Use Open MPI's internal copy of libltdl.
-    external:    Use an external libltdl installation (rely on default
-                 compiler and linker paths to find it)
-    <no value>:  Same as "internal".
-    <directory>: Specify the location of a specific libltdl
-                 installation to use
-
-  By default (or if --with-libltdl is specified with no VALUE), Open
-  MPI will build and use the copy of libltdl that it has in its source
-  tree.  However, if the VALUE is "external", Open MPI will look for
-  the relevant libltdl header file and library in default compiler /
-  linker locations.  Or, VALUE can be a directory tree where the
-  libltdl header file and library can be found.  This option allows
-  operating systems to include Open MPI and use their default libltdl
-  installation instead of Open MPI's bundled libltdl.
-
-  Note that this option is ignored if --disable-dlopen is specified.
-
 --disable-libompitrace
   Disable building the simple "libompitrace" library (see note above
   about libompitrace)

autogen.pl

@@ -1,6 +1,6 @@
 #!/usr/bin/env perl
 #
-# Copyright (c) 2009-2014 Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2009-2015 Cisco Systems, Inc.  All rights reserved.
 # Copyright (c) 2010      Oracle and/or its affiliates.  All rights reserved.
 # Copyright (c) 2013      Mellanox Technologies, Inc.
 #                         All rights reserved.
@@ -1265,7 +1265,6 @@ sub patch_autotools_output {
 verbose "==> Remove stale files\n";
 find_and_delete(qw/config.guess config.sub depcomp compile install-sh ltconfig
     ltmain.sh missing mkinstalldirs libtool/);
-system("rm -rf opal/libltdl");
 
 # Remove the old m4 file and write the new one
 verbose "==> Writing m4 file with autogen.pl results\n";
@@ -1292,22 +1291,9 @@ sub patch_autotools_output {
 
 #---------------------------------------------------------------------------
 
-# For FreeBSD (carried over from autogen.sh); apparently some versions
-# of automake don't so this (prior to 1.9.7...?).
-system("chmod u+w opal/libltdl/configure");
-
-#---------------------------------------------------------------------------
-
 ++$step;
 verbose "\n$step. Patching autotools output on top-level tree :-(\n\n";
 
-# Patch preopen error in libltdl
-if (-f "opal/libltdl/loaders/preopen.c") {
-    verbose "=== Patching preopen error masking in libltdl\n";
-    safe_system("$patch_prog -N -p0 < config/libltdl-preopen-error.diff");
-    unlink("opal/libltdl/loaders/preopen.c.rej");
-}
-
 patch_autotools_output(".");
 
 #---------------------------------------------------------------------------

config/Makefile.am

@@ -9,7 +9,7 @@
 #                         University of Stuttgart.  All rights reserved.
 # Copyright (c) 2004-2005 The Regents of the University of California.
 #                         All rights reserved.
-# Copyright (c) 2006-2010 Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2006-2015 Cisco Systems, Inc.  All rights reserved.
 # Copyright (c) 2010      Oracle and/or its affiliates.  All rights 
 #                         reserved.
 # Copyright (c) 2014      Intel, Inc. All rights reserved.
@@ -23,7 +23,6 @@
 EXTRA_DIST = \
         distscript.csh \
 	opal_get_version.m4sh \
-	libltdl-preopen-error.diff \
 	ltmain_pgi_tp.diff \
         opal_mca_priority_sort.pl
 

config/opal_configure_options.m4

@@ -10,7 +10,7 @@ dnl Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
 dnl                         University of Stuttgart.  All rights reserved.
 dnl Copyright (c) 2004-2005 The Regents of the University of California.
 dnl                         All rights reserved.
-dnl Copyright (c) 2006-2014 Cisco Systems, Inc.  All rights reserved.
+dnl Copyright (c) 2006-2015 Cisco Systems, Inc.  All rights reserved.
 dnl Copyright (c) 2007      Sun Microsystems, Inc.  All rights reserved.
 dnl Copyright (c) 2009      IBM Corporation.  All rights reserved.
 dnl Copyright (c) 2009      Los Alamos National Security, LLC.  All rights
@@ -292,13 +292,17 @@ AC_ARG_ENABLE([dlopen],
                      Disabling dlopen implies --disable-mca-dso.
                      (default: enabled)])])
 if test "$enable_dlopen" = "no" ; then
-    enable_mca_dso="no"
-    enable_mca_static="yes"
     OPAL_ENABLE_DLOPEN_SUPPORT=0
     AC_MSG_RESULT([no])
-else
+elif test "$enable_dlopen" = "yes"; then
     OPAL_ENABLE_DLOPEN_SUPPORT=1
     AC_MSG_RESULT([yes])
+elif test $OPAL_DEVEL -eq 1; then
+    OPAL_ENABLE_DLOPEN_SUPPORT=1
+    AC_MSG_RESULT([yes (devel build default)])
+else
+    OPAL_ENABLE_DLOPEN_SUPPORT=-1
+    AC_MSG_RESULT([if available])
 fi