[libgsf] configure: don't use Werror=... flags that hit system headers.

[Morten Welinder <mortenw src gnome org>]

commit 7401d284594e18c393c4319040697118e8f37154
Author: Morten Welinder <terra gnome org>
Date:   Thu Aug 1 18:29:37 2013 -0400

    configure: don't use Werror=... flags that hit system headers.

 ChangeLog    |    5 +++++
 NEWS         |    1 +
 configure.ac |    4 +++-
 3 files changed, 9 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 65887ac..b58af97 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2013-08-01  Morten Welinder <terra gnome org>
+
+       * configure.ac (set_more_warnings): When checking for warnings
+       flags, include <stdio.h> for mingw's benefit.
+
 2013-07-30  Jean Brefort  <jean brefort normalesup org>
 
        * gsf/gsf-libxml.c (gsf_xml_parser_context_full): allow the huge libxml
diff --git a/NEWS b/NEWS
index 162b483..204d6be 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,7 @@ Jean:
 
 Morten:
        * Fix problem with bogus metadata.  [#703952]
+       * Avoid interaction problems between Werror and system headers.
 
 --------------------------------------------------------------------------
 libgsf 1.14.27
diff --git a/configure.ac b/configure.ac
index 1cf2964..2864e2b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -214,8 +214,10 @@ if test "$GCC" = yes -a "x$set_more_warnings" != xno; then
                SAVE_CFLAGS="$CFLAGS"
                CFLAGS="$CFLAGS $uwoption $option"
                AC_MSG_CHECKING([whether gcc understands $option])
+               dnl Include a system header so we ignore Werror=... flags
+               dnl that cause trouble.
                AC_COMPILE_IFELSE(
-                       [AC_LANG_PROGRAM([], [])],
+                       [AC_LANG_PROGRAM([[#include <stdio.h>]], [])],
                        [has_option=yes],
                        [has_option=no])
                CFLAGS="$SAVE_CFLAGS"