libcompat: remove

The old libcompat compatibility library no longer has any users.
Remove it.

configure.ac

@@ -389,7 +389,6 @@ AC_CONFIG_FILES( \
   src/common/libkvs/Makefile \
   src/common/libjob/Makefile \
   src/common/libsubprocess/Makefile \
-  src/common/libcompat/Makefile \
   src/common/liboptparse/Makefile \
   src/common/libidset/Makefile \
   src/common/libtomlc99/Makefile \

src/common/Makefile.am

@@ -6,7 +6,6 @@ SUBDIRS = libtap \
 	  libflux \
 	  libkvs \
 	  libjob \
-	  libcompat \
 	  liboptparse \
 	  libidset \
 	  libtomlc99 \
@@ -26,7 +25,6 @@ libflux_internal_la_LIBADD = \
 	$(builddir)/libutil/libutil.la \
 	$(builddir)/libidset/libidset.la \
 	$(builddir)/libev/libev.la \
-	$(builddir)/libcompat/libcompat.la \
 	$(builddir)/libtomlc99/libtomlc99.la \
 	$(JANSSON_LIBS) $(ZMQ_LIBS) $(LIBPTHREAD) $(LIBUTIL) \
 	$(LIBDL) $(LIBRT) $(FLUX_SECURITY_LIBS) $(LIBSODIUM_LIBS)