Add missing mmintrin.h header entry

Author: rnk

clang/include/clang/Basic/BuiltinHeaders.def

@@ -22,6 +22,7 @@ HEADER(INTRIN_H, "intrin.h")
 HEADER(MALLOC_H, "malloc.h")
 HEADER(MATH_H, "math.h")
 HEADER(MEMORY, "memory")
+HEADER(MMINTRIN_H, "mmintrin.h")
 HEADER(OBJC_MESSAGE_H, "objc/message.h")
 HEADER(OBJC_OBJC_AUTO_H, "objc/objc-auto.h")
 HEADER(OBJC_OBJC_EXCEPTION_H, "objc/objc-exception.h")