Add COMPILER_RT_ABI attribute to declarations of builtin functions in unittests

Summary:
This makes their local declarations match their definitions for ARM targets,
where they have a different calling convention.

This really only affects functions that use floating point types (since the
runtime functions use soft-float, and some targets may default to hard-float)
but it seemed good to make it uniform and do the int-only ones too.

Differential Revision: http://reviews.llvm.org/D9062

llvm-svn: 235722
diff --git a/compiler-rt/test/builtins/Unit/cmpdi2_test.c b/compiler-rt/test/builtins/Unit/cmpdi2_test.c
index 609ab1a..33a12a0 100644
--- a/compiler-rt/test/builtins/Unit/cmpdi2_test.c
+++ b/compiler-rt/test/builtins/Unit/cmpdi2_test.c
@@ -18,7 +18,7 @@
 //           if (a == b) returns 1
 //           if (a >  b) returns 2
 
-si_int __cmpdi2(di_int a, di_int b);
+COMPILER_RT_ABI si_int __cmpdi2(di_int a, di_int b);
 
 int test__cmpdi2(di_int a, di_int b, si_int expected)
 {