[compiler-rt] [tests] Add missing "int_lib.h" includes and extend guards

[mgorny]

Summary

Fix missing "int_lib.h" includes in ARM negdf2vfp and subdf3vfp tests.
Additionally, extend the arm guard to cover the builtin definition
in the former. This is mostly intended to prevent build failures
and allow those tests to be properly skipped on other targets.

[rengolin]

LGTM. Thanks!

compiler-rt/trunk/test/builtins/Unit/negdf2vfp_test.c

 //===-- negdf2vfp_test.c - Test __negdf2vfp -------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file tests __negdf2vfp for the compiler_rt library.
 //
 //===----------------------------------------------------------------------===//
 
+#include "int_lib.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <math.h>
 
 
+#if __arm__
 extern COMPILER_RT_ABI double __negdf2vfp(double a);
 
-#if __arm__
 int test__negdf2vfp(double a)
 {
     double actual = __negdf2vfp(a);
     double expected = -a;
     if (actual != expected)
         printf("error in test__negdf2vfp(%f) = %f, expected %f\n",
                a, actual, expected);
     return actual != expected;

compiler-rt/trunk/test/builtins/Unit/subdf3vfp_test.c

 //===-- subdf3vfp_test.c - Test __subdf3vfp -------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file tests __subdf3vfp for the compiler_rt library.
 //
 //===----------------------------------------------------------------------===//
 
+#include "int_lib.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <math.h>
 
 
 #if __arm__
 extern COMPILER_RT_ABI double __subdf3vfp(double a, double b);