[FrontendTests] Try again to make test not write an output file

Setting the output stream to nulls seems to work.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@375491 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/Frontend/OutputStreamTest.cpp

diff --git a/unittests/Frontend/OutputStreamTest.cpp b/unittests/Frontend/OutputStreamTest.cpp
index 14537ec..6a867bf 100644
--- a/unittests/Frontend/OutputStreamTest.cpp
+++ b/unittests/Frontend/OutputStreamTest.cpp
@@ -58,6 +58,7 @@
   std::string VerboseBuffer;
   raw_string_ostream VerboseStream(VerboseBuffer);
 
+  Compiler.setOutputStream(std::make_unique<raw_null_ostream>());
   Compiler.setInvocation(std::move(Invocation));
   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
   Compiler.createDiagnostics(
@@ -86,6 +87,7 @@
     std::unique_ptr<raw_ostream> VerboseStream =
         std::make_unique<raw_string_ostream>(VerboseBuffer);
 
+    Compiler.setOutputStream(std::make_unique<raw_null_ostream>());
     Compiler.setInvocation(std::move(Invocation));
     IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
     Compiler.createDiagnostics(