Introduce CRT_HAS_128BIT, currently for all __LP64__ platforms.
Use it to enable the various functions for TI mode.

llvm-svn: 201909
diff --git a/compiler-rt/lib/builtins/negti2.c b/compiler-rt/lib/builtins/negti2.c
index f7e4ad3..28ef941 100644
--- a/compiler-rt/lib/builtins/negti2.c
+++ b/compiler-rt/lib/builtins/negti2.c
@@ -14,7 +14,7 @@
 
 #include "int_lib.h"
 
-#if __x86_64
+#ifdef CRT_HAS_128BIT
 
 /* Returns: -a */
 
@@ -27,4 +27,4 @@
     return -a;
 }
 
-#endif
+#endif /* CRT_HAS_128BIT */