[C++11] Now that the users are gone, rip out the duplicated traits from type_traits.h

Simplify the remaining ones a bit.

llvm-svn: 203249
diff --git a/llvm/unittests/IR/ValueMapTest.cpp b/llvm/unittests/IR/ValueMapTest.cpp
index 176b56c..6fd87b1 100644
--- a/llvm/unittests/IR/ValueMapTest.cpp
+++ b/llvm/unittests/IR/ValueMapTest.cpp
@@ -116,7 +116,8 @@
 
 template<typename ExpectedType, typename VarType>
 void CompileAssertHasType(VarType) {
-  static_assert((is_same<ExpectedType, VarType>::value), "Not the same type");
+  static_assert(std::is_same<ExpectedType, VarType>::value,
+                "Not the same type");
 }
 
 TYPED_TEST(ValueMapTest, Iteration) {