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/clzti2_test.c b/compiler-rt/test/builtins/Unit/clzti2_test.c
index 5a0e3e8..3a2c6fa 100644
--- a/compiler-rt/test/builtins/Unit/clzti2_test.c
+++ b/compiler-rt/test/builtins/Unit/clzti2_test.c
@@ -20,7 +20,7 @@
 
 // Precondition: a != 0
 
-si_int __clzti2(ti_int a);
+COMPILER_RT_ABI si_int __clzti2(ti_int a);
 
 int test__clzti2(ti_int a, si_int expected)
 {