[C++11] Replace LLVM-style type traits with C++11 standard ones.

No functionality change.

llvm-svn: 203242
diff --git a/llvm/unittests/ADT/HashingTest.cpp b/llvm/unittests/ADT/HashingTest.cpp
index 1b3d061..60917ae 100644
--- a/llvm/unittests/ADT/HashingTest.cpp
+++ b/llvm/unittests/ADT/HashingTest.cpp
@@ -41,7 +41,7 @@
 
 namespace hashing {
 namespace detail {
-template <> struct is_hashable_data<LargeTestInteger> : true_type {};
+template <> struct is_hashable_data<LargeTestInteger> : std::true_type {};
 } // namespace detail
 } // namespace hashing