[X86] Add missing m64/int64 conversions

Define the 64-bit equivalents of _m_to_int and _m_from_int.

Differential Revision: http://reviews.llvm.org/D15572

llvm-svn: 256122
diff --git a/clang/lib/Headers/mmintrin.h b/clang/lib/Headers/mmintrin.h
index 1a9eb10..162cb1a 100644
--- a/clang/lib/Headers/mmintrin.h
+++ b/clang/lib/Headers/mmintrin.h
@@ -443,7 +443,9 @@
 /* Aliases for compatibility. */
 #define _m_empty _mm_empty
 #define _m_from_int _mm_cvtsi32_si64
+#define _m_from_int64 _mm_cvtsi64_m64
 #define _m_to_int _mm_cvtsi64_si32
+#define _m_to_int64 _mm_cvtm64_si64
 #define _m_packsswb _mm_packs_pi16
 #define _m_packssdw _mm_packs_pi32
 #define _m_packuswb _mm_packs_pu16