[Pixman] [PATCH] Make sure iwMMXt is only detected on ARM

[Matt Turner]

I'm not able to reproduce it, but I have two reports that iwMMXt is
incorrectly detected on x86 and amd64. This happens because it uses the
standard _mm_* intrinsic functions. It should fail on x86 and amd64
because configure will use -march=iwmmxt to compile the test, which
isn't a valid option on these platforms.

So, just #error out in the test if the __arm__ preprocessor directive
isn't defined.

Fixes https://bugs.gentoo.org/show_bug.cgi?id=385179

Signed-off-by: Matt Turner <mattst88 at gmail.com>
---
 configure.ac |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/configure.ac b/configure.ac
index 481d0bb..471a127 100644
--- a/configure.ac
+++ b/configure.ac
@@ -552,6 +552,9 @@ AC_MSG_CHECKING(whether to use ARM IWMMXT intrinsics)
 xserver_save_CFLAGS=$CFLAGS
 CFLAGS="$IWMMXT_CFLAGS $CFLAGS"
 AC_COMPILE_IFELSE([
+#ifndef __arm__
+#error "IWMMXT is only available on ARM"
+#endif
 #if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 3 && __GNUC_MINOR__ < 6))
 #error "Need GCC >= 4.6 for IWMMXT intrinsics"
 #endif
-- 
1.7.3.4