[clang-tools-extra] Migrate llvm::make_unique to std::make_unique

Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.

Differential revision: https://reviews.llvm.org/D66259

llvm-svn: 368944
diff --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
index 1bdfe21..2795cab 100644
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
@@ -243,7 +243,7 @@
 void IdentifierNamingCheck::registerPPCallbacks(
     const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
   ModuleExpanderPP->addPPCallbacks(
-      llvm::make_unique<IdentifierNamingCheckPPCallbacks>(ModuleExpanderPP,
+      std::make_unique<IdentifierNamingCheckPPCallbacks>(ModuleExpanderPP,
                                                           this));
 }