Fix C++ convenience libraries

[Greg Hudson]

When you create a C++ convenience library, postdeps causes your
convenience library to link against -lstdc++ and friends.  I don't
know if it even makes sense to link a convenience library against an
installed library--perhaps it should be an error to try--and it
doesn't work when the installed library is static.  (For details, see
http://mail.gnu.org/archive/html/libtool/2003-08/msg00027.html and, if
it ever gets through, my response.)

This patch makes libtool ignore postdeps when building a convenience
library.  There may be better approaches.

Index: ltmain.in
===================================================================
RCS file: /cvsroot/libtool/libtool/ltmain.in,v
retrieving revision 1.341
diff -u -r1.341 ltmain.in
--- ltmain.in   31 Jul 2003 20:41:34 -0000      1.341
+++ ltmain.in   24 Aug 2003 06:53:32 -0000
@@ -1733,6 +1733,10 @@
     done
 
     if test "$linkmode" = lib; then
+      if test -z "$rpath"; then
+       # Don't use postdeps when building a convenience library.
+       postdeps=
+      fi
       libs="$predeps $libs $compiler_lib_search_path $postdeps"
 
       # Compute libraries that are listed more than once in $predeps