Did you put it in the toplevel configure.in or in
libgfortran/configure.ac? I suspect it needs to be in the former,
because the latter probably shares the same config.cache and thus it
won't be checked a second time when running configure for libgfortran.
Tried to put it into the toplevel configure.ac, but there is no
AC_PROG_LIBTOOL there, so I put it somewhere near other AC_ macros
(see patch below). Autoconf then says:
$ autoconf
configure.ac:1071: error: possibly undefined macro: AC_LIBTOOL_WIN32_DLL
If this token and others are legitimate, please use
m4_pattern_allow.
See the Autoconf documentation.
Index: configure.ac
===================================================================
--- configure.ac (revision 122655)
+++ configure.ac (working copy)
@@ -1068,6 +1068,8 @@
fi
fi
+AC_LIBTOOL_WIN32_DLL
+
ACX_PROG_GNAT
ACX_PROG_CMP_IGNORE_INITIAL
