add --cpan-package-reject-from-depends option to filter auto-depends

The auto-depends for cpan modules worked well on rpm because of the
use of capabilities (ie: perl(IO::Handle)) but deb packages of CPAN
modules generate dependencies that might not exist because they are
provided by another package and therefore need to be filtered out.

For instance, perl(IO::Handle) would be turned into libio-handle-perl,
and that package doesn't exist.  The IO/Handle.pm file is actually in
package perl-base.

Prior to this patch, fpm would filter out a short list of
modules (vars, warnings, strict, and Config) and with this patch you
can add to that list with --cpan-package-reject-from-depends.

docs/cli-reference.rst

@@ -228,6 +228,9 @@ General Options
 * ``--cpan-package-name-postfix NAME_POSTFIX``
     - (cpan only) Name to prefix the package name with.
 
+* ``--cpan-package-reject-from-depends MODULE``
+    - (cpan only) Filter modules from the generated depends.
+
 * ``--[no-]cpan-test``
     - (cpan only) Run the tests before packaging?
 
@@ -668,6 +671,8 @@ cpan
     - Name to prefix the package name with.
 * ``--cpan-package-name-postfix NAME_POSTFIX``
     - Name to prefix the package name with.
+* ``--cpan-package-reject-from-depends MODULE``
+    - (cpan only) Filter modules from the generated depends.
 * ``--cpan-perl-bin PERL_EXECUTABLE``
     - The path to the perl executable you wish to run.
 * ``--cpan-perl-lib-path PERL_LIB_PATH``

docs/packages/cli/cpan.rst

@@ -16,6 +16,8 @@
     - Name to prefix the package name with.
 * ``--cpan-package-name-postfix NAME_POSTFIX``
     - Name to prefix the package name with.
+* ``--cpan-package-reject-from-depends MODULE``
+    - Remove module from those generated with auto-depend.
 * ``--cpan-perl-bin PERL_EXECUTABLE``
     - The path to the perl executable you wish to run.
 * ``--cpan-perl-lib-path PERL_LIB_PATH``

lib/fpm/package/cpan.rb

@@ -25,6 +25,13 @@ class FPM::Package::CPAN < FPM::Package
   option "--package-name-postfix", "NAME_POSTFIX",
     "Name to prefix the package name with.", :default => ""
 
+  option "--package-reject-from-depends", "MODULE",
+    "Filter modules matching MODULE from those generated by " \
+    "the auto-depends for CPAN modules. This flag can be specified " \
+    "multiple times. Use the perl module name, IE: URI::Escape.",
+    :multivalued => true, :attribute_name => :rejects,
+    :default => ['vars','warnings','strict','Config']
+
   option "--test", :flag,
     "Run the tests before packaging?", :default => true
 

lib/fpm/package/deb.rb

@@ -707,7 +707,9 @@ def converted_from(origin)
         end
       end
 
-      rejects = [ "perl(vars)", "perl(warnings)", "perl(strict)", "perl(Config)" ]
+      rejects = attributes[:rejects].map do |skip|
+        "perl(#{skip})"
+      end
       self.dependencies = self.dependencies.reject do |dep|
         # Reject non-module Perl dependencies like 'vars' and 'warnings'
         rejects.include?(dep)