aclocal: Use -Werror when checking compiler flags.

[Per Johansson]

This makes clang exit with error on unsupported warnings.
---
 aclocal.m4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/aclocal.m4 b/aclocal.m4
index 14cf916..31193cf 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -74,7 +74,7 @@ AC_DEFUN([WINE_TRY_CFLAGS],
 [AS_VAR_PUSHDEF([ac_var], ac_cv_cflags_[[$1]])dnl
 AC_CACHE_CHECK([whether the compiler supports $1], ac_var,
 [ac_wine_try_cflags_saved=$CFLAGS
-CFLAGS="$CFLAGS $1"
+CFLAGS="$CFLAGS -Werror $1"
 AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(int argc, char **argv) { return 0; }]])],
                [AS_VAR_SET(ac_var,yes)], [AS_VAR_SET(ac_var,no)])
 CFLAGS=$ac_wine_try_cflags_saved])
-- 
1.8.0