Fix test to output LLVM to a temporary file, which we grep as part of the test

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@69448 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGenObjC/overloadable.m b/test/CodeGenObjC/overloadable.m
index 1cc501a..d455edf 100644
--- a/test/CodeGenObjC/overloadable.m
+++ b/test/CodeGenObjC/overloadable.m
@@ -1,5 +1,5 @@
 // rdar://6657613
-// RUN: clang-cc -emit-llvm %s -o -
+// RUN: clang-cc -emit-llvm %s -o %t
 
 @class C;