libgfortran does not respect --disable-werror

https://bugs.gentoo.org/433435
http://gcc.gnu.org/PR54724


--- a/libgfortran/configure
+++ b/libgfortran/configure
@@ -5764,7 +5764,7 @@ fi
 
 # Add -Wall -fno-repack-arrays -fno-underscoring if we are using GCC.
 if test "x$GCC" = "xyes"; then
-  AM_FCFLAGS="-I . -Wall -Werror -fimplicit-none -fno-repack-arrays -fno-underscoring"
+  AM_FCFLAGS="-I . -Wall -fimplicit-none -fno-repack-arrays -fno-underscoring"
   ## We like to use C99 routines when available.  This makes sure that
   ## __STDC_VERSION__ is set such that libc includes make them available.
   AM_CFLAGS="-std=gnu99 -Wall -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wextra -Wwrite-strings"