Revert r326092: [gtest] Add PrintTo overload for StringRef.

It seems to break the following buildbot:
http://lab.llvm.org:8011/builders/sanitizer-windows/builds/24729

Will resubmit after investigating and fixing it.

llvm-svn: 326096

llvm/utils/unittest/googletest/include/gtest/internal/custom/gtest-printers.h

@@ -39,17 +39,4 @@
 #ifndef GTEST_INCLUDE_GTEST_INTERNAL_CUSTOM_GTEST_PRINTERS_H_
 #define GTEST_INCLUDE_GTEST_INTERNAL_CUSTOM_GTEST_PRINTERS_H_
 
-#include "llvm/ADT/StringRef.h"
-#include "llvm/Support/raw_os_ostream.h"
-#include <cassert>
-
-namespace llvm {
-// Without this overload StringRef will be printed as a generic container.
-inline void PrintTo(const llvm::StringRef &Val, std::ostream *S) {
-  assert(S);
-  llvm::raw_os_ostream OS(*S);
-  OS << Val;
-}
-} // namespace llvm
-
 #endif  // GTEST_INCLUDE_GTEST_INTERNAL_CUSTOM_GTEST_PRINTERS_H_