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/floatundidf_test.c b/compiler-rt/test/builtins/Unit/floatundidf_test.c
index ae91ac3..97fb1e5 100644
--- a/compiler-rt/test/builtins/Unit/floatundidf_test.c
+++ b/compiler-rt/test/builtins/Unit/floatundidf_test.c
@@ -22,7 +22,7 @@
 
 // seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
 
-double __floatundidf(du_int a);
+COMPILER_RT_ABI double __floatundidf(du_int a);
 
 int test__floatundidf(di_int a, double expected)
 {