unittests: explicit stringify StringRefs for conversion

When clang is built outside of the LLVM tree (against a corresponding version),
there is no definition providing for operator<<(std::ostream &, StringRef) which
is required for the assertion routines in google-test tests.  Avoid the
compilation failure by explicitly stringifying the StringRef prior to use.

llvm-svn: 200096
diff --git a/clang/unittests/AST/DeclPrinterTest.cpp b/clang/unittests/AST/DeclPrinterTest.cpp
index ade55aa..66da386 100644
--- a/clang/unittests/AST/DeclPrinterTest.cpp
+++ b/clang/unittests/AST/DeclPrinterTest.cpp
@@ -77,7 +77,8 @@
   OwningPtr<FrontendActionFactory> Factory(newFrontendActionFactory(&Finder));
 
   if (!runToolOnCodeWithArgs(Factory->create(), Code, Args, FileName))
-    return testing::AssertionFailure() << "Parsing error in \"" << Code << "\"";
+    return testing::AssertionFailure()
+      << "Parsing error in \"" << Code.str() << "\"";
 
   if (Printer.getNumFoundDecls() == 0)
     return testing::AssertionFailure()
@@ -90,8 +91,8 @@
 
   if (Printer.getPrinted() != ExpectedPrinted)
     return ::testing::AssertionFailure()
-      << "Expected \"" << ExpectedPrinted << "\", "
-         "got \"" << Printer.getPrinted() << "\"";
+      << "Expected \"" << ExpectedPrinted.str() << "\", "
+         "got \"" << Printer.getPrinted().str() << "\"";
 
   return ::testing::AssertionSuccess();
 }