Consistently use COMPILER_RT_ABI for all public symbols.
Move prototypes into headers and fix a few inconsistencies.

llvm-svn: 202591
diff --git a/compiler-rt/lib/builtins/fixunsxfsi.c b/compiler-rt/lib/builtins/fixunsxfsi.c
index b9da86c..df0a18e 100644
--- a/compiler-rt/lib/builtins/fixunsxfsi.c
+++ b/compiler-rt/lib/builtins/fixunsxfsi.c
@@ -30,7 +30,7 @@
  * 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
  */
 
-su_int
+COMPILER_RT_ABI su_int
 __fixunsxfsi(long double a)
 {
     long_double_bits fb;