reland [gtest] Fix printing of StringRef and SmallString in assert messages.

Renames GTEST_NO_LLVM_RAW_OSTREAM -> GTEST_NO_LLVM_SUPPORT and guards
the new features behind it.

This reverts commit a063bcf3ef5a879adbe9639a3c187d876eee0e66.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@369527 91177308-0d34-0410-b5e6-96231b3b80d8

Author: sammccall

tests/FuzzerUnittest.cpp

@@ -6,8 +6,8 @@
 // with ASan) involving C++ standard library types when using libcxx.
 #define _LIBCPP_HAS_NO_ASAN
 
-// Do not attempt to use LLVM ostream from gtest.
-#define GTEST_NO_LLVM_RAW_OSTREAM 1
+// Do not attempt to use LLVM ostream etc from gtest.
+#define GTEST_NO_LLVM_SUPPORT 1
 
 #include "FuzzerCorpus.h"
 #include "FuzzerDictionary.h"