[PATCH] fix for Darwin shared library support

[Joe Orton]

Christian Schaffner tracked down a bug where libtool HEAD fails
to detect shared library support in the linker on Darwin.

This occurs in a configure script using AC_LIBTOOL_TAGS([]), because
AC_LIBTOOL_PROG_LD_SHLIBS is using $GXX not $GCC, but $GXX is not set.
The fix Christian wrote is below.  

Is there an alternative to using AC_LIBTOOL_TAGS([]) - without this I
can't seem to produce a configure script which works on a system without
a C++ compiler?

Index: m4/libtool.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/m4/libtool.m4,v
retrieving revision 1.8
diff -u -r1.8 libtool.m4
--- m4/libtool.m4       21 Oct 2003 15:03:56 -0000      1.8
+++ m4/libtool.m4       28 Oct 2003 16:46:41 -0000
@@ -5482,7 +5482,7 @@
       ;;
 
     darwin* | rhapsody*)
-    if test "$GXX" = yes ; then
+    if test "$GCC" = yes ; then
       _LT_AC_TAGVAR(archive_cmds_need_lc, $1)=no
       case "$host_os" in
       rhapsody* | darwin1.[[012]])