[libsoup/gnome-2-26: 25/29] Fix cflags to work with older versions of gcc

[Dan Winship <danw src gnome org>]

commit d09fbdcda8ad2643a086ae803f0d20976f78056c
Author: Dan Winship <danw gnome org>
Date:   Sun Apr 19 10:46:40 2009 -0400

    Fix cflags to work with older versions of gcc
    
    Check that gcc supports -Wmissing-include-dirs and -Wundef rather than
    using them unconditionally.
    
    http://bugzilla.gnome.org/show_bug.cgi?id=578851
---
 configure.in |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/configure.in b/configure.in
index 529c9a6..4e44482 100644
--- a/configure.in
+++ b/configure.in
@@ -241,8 +241,20 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
 		-Wall -Wstrict-prototypes -Wmissing-declarations \
 		-Wmissing-prototypes -Wnested-externs -Wpointer-arith \
 		-Wdeclaration-after-statement -Wformat=2 -Winit-self \
-		-Wmissing-include-dirs -Wundef -Waggregate-return \
-		-Wmissing-format-attribute"
+		-Waggregate-return -Wmissing-format-attribute"
+
+	for option in -Wmissing-include-dirs -Wundef; do
+		SAVE_CFLAGS="$CFLAGS"
+		CFLAGS="$CFLAGS $option"
+		AC_MSG_CHECKING([whether gcc understands $option])
+		AC_TRY_COMPILE([], [],
+			has_option=yes,
+			has_option=no,)
+		AC_MSG_RESULT($has_option)
+		if test $has_option = no; then
+			CFLAGS="$SAVE_CFLAGS"
+		fi
+	done
 fi
 
 if test "$os_win32" != yes; then