[gegl] Check for compiler flags before using them

[Michael Schumacher <schumaml src gnome org>]

commit 0a2720b1d546a850e726c9ec5c66a43e3ae6b8b6
Author: Michael Schumacher <schumaml gmx de>
Date:   Fri Dec 17 20:54:48 2010 +0100

    Check for compiler flags before using them

 configure.ac |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index f0f9c72..67bfc96 100644
--- a/configure.ac
+++ b/configure.ac
@@ -357,7 +357,9 @@ if test "x$enable_mmx" = "xyes"; then
     AC_MSG_RESULT(yes)
 
     if test "x$enable_sse" = "xyes"; then
-      AS_COMPILER_FLAG([-msse], [SSE_EXTRA_CFLAGS="-msse -ftree-vectorize -ffast-math"])
+      AS_COMPILER_FLAG([-msse], [SSE_EXTRA_CFLAGS="-msse"])
+      AS_COMPILER_FLAG([-ftree-vectorize], [SSE_EXTRA_CFLAGS="$SSE_EXTRA_CFLAGS -ftree-vectorize"])
+      AS_COMPILER_FLAG([-ffast-math], [SSE_EXTRA_CFLAGS="$SSE_EXTRA_CFLAGS -ffast-math"])
 
       AC_MSG_CHECKING(whether we can compile SSE code)