[babl] extensions: Only build sse-half for x86_64.

[Michael Henning <mhenning src gnome org>]

commit 0cbef4132cd6a7f656169c47fb1fb7533cb24d37
Author: Michael Henning <drawoc darkrefraction com>
Date:   Sun Jan 3 19:00:29 2016 -0500

    extensions: Only build sse-half for x86_64.
    
    _mm_insert_epi64 is only available on 64-bit

 extensions/sse-half.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/extensions/sse-half.c b/extensions/sse-half.c
index ca57ceb..e20c214 100644
--- a/extensions/sse-half.c
+++ b/extensions/sse-half.c
@@ -18,7 +18,7 @@
 
 #include "config.h"
 
-#if defined(USE_SSE4_1) && defined(USE_F16C)
+#if defined(USE_SSE4_1) && defined(USE_F16C) && defined(ARCH_X86_64)
 
 #include <immintrin.h>
 
@@ -131,14 +131,14 @@ conv_rgbaF_rgbaHalf (const float *src, uint16_t *dst, long samples)
   return conv_yF_yHalf (src, dst, samples * 4) / 4;
 }
 
-#endif /* defined(USE_SSE4_1) && defined(USE_F16C) */
+#endif /* defined(USE_SSE4_1) && defined(USE_F16C) && defined(ARCH_X86_64) */
 
 int init (void);
 
 int
 init (void)
 {
-#if defined(USE_SSE4_1) && defined(USE_F16C)
+#if defined(USE_SSE4_1) && defined(USE_F16C) && defined(ARCH_X86_64)
   const Babl *rgbaF_linear = babl_format_new (
     babl_model ("RGBA"),
     babl_type ("float"),
@@ -263,7 +263,7 @@ init (void)
       CONV(yF,       yHalf);
     }
 
-#endif /* defined(USE_SSE4_1) && defined(USE_F16C) */
+#endif /* defined(USE_SSE4_1) && defined(USE_F16C) && defined(ARCH_X86_64) */
 
   return 0;
 }