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/floatuntixf.c b/compiler-rt/lib/builtins/floatuntixf.c
index dbce80f..d607cc3 100644
--- a/compiler-rt/lib/builtins/floatuntixf.c
+++ b/compiler-rt/lib/builtins/floatuntixf.c
@@ -14,7 +14,7 @@
 
 #include "int_lib.h"
 
-#if __x86_64
+#ifdef CRT_HAS_128BIT
 
 /* Returns: convert a to a long double, rounding toward even. */