Fix test to not write output to the test directory, as it may not be writable.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@217337 91177308-0d34-0410-b5e6-96231b3b80d8

test/Modules/warn-unused-local-typedef.cpp

 // RUN: rm -rf %t
-// RUN: %clang -Wunused-local-typedef -c -x objective-c++ -fcxx-modules -fmodules -fmodules-cache-path=%t -I %S/Inputs %s 2>&1 | FileCheck %s -check-prefix=CHECK_1
-// RUN: %clang -Wunused-local-typedef -c -x objective-c++ -fcxx-modules -fmodules -fmodules-cache-path=%t -I %S/Inputs %s 2>&1 | FileCheck %s -check-prefix=CHECK_2 -allow-empty
+// RUN: %clang -Wunused-local-typedef -c -x objective-c++ -fcxx-modules -fmodules -fmodules-cache-path=%t -I %S/Inputs %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=CHECK_1
+// RUN: %clang -Wunused-local-typedef -c -x objective-c++ -fcxx-modules -fmodules -fmodules-cache-path=%t -I %S/Inputs %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=CHECK_2 -allow-empty
 
 // For modules, the warning should only fire the first time, when the module is
 // built.