[PATCH weston] Build: Silence shift-negative-value warning

[Daniel Stone]

Pixman's headers include a representation of -1 in fixed-point, which is
-1 << 16. This trips a GCC warning about shifting negative values. As we
can't do much about it, just silence the warning.

Signed-off-by: Daniel Stone <daniels at collabora.com>
---
 configure.ac | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 5364c59..f2638fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -547,7 +547,8 @@ AM_CONDITIONAL(BUILD_SETBACKLIGHT, test "x$enable_setbacklight" = "xyes")
 
 if test "x$GCC" = "xyes"; then
 	GCC_CFLAGS="-Wall -Wextra -Wno-unused-parameter \
-		-Wno-missing-field-initializers -g -fvisibility=hidden \
+		-Wno-shift-negative-value -Wno-missing-field-initializers \
+		-g -fvisibility=hidden \
 		-Wstrict-prototypes -Wmissing-prototypes -Wsign-compare"
 fi
 AC_SUBST(GCC_CFLAGS)
-- 
2.7.4