Fix leak from r210059

Also revert r210096 which temporarily disabled the test while this was being
investigated.

llvm-svn: 210115

clang/lib/Frontend/CompilerInstance.cpp

@@ -478,6 +478,12 @@ CompilerInstance::createDefaultOutputFile(bool Binary,
                           /*UseTemporary=*/true);
 }
 
+llvm::raw_null_ostream *CompilerInstance::createNullOutputFile() {
+  llvm::raw_null_ostream *OS = new llvm::raw_null_ostream();
+  addOutputFile(OutputFile("", "", OS));
+  return OS;
+}
+
 llvm::raw_fd_ostream *
 CompilerInstance::createOutputFile(StringRef OutputPath,
                                    bool Binary, bool RemoveFileOnSignal,