[Clang] 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: 368942
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 5d6f17e..d5ef7db 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -8729,7 +8729,7 @@
        /* In loop */) {
     FunctionDecl *FD = cast<FunctionDecl>(GetDecl(LateParsedTemplates[Idx++]));
 
-    auto LT = llvm::make_unique<LateParsedTemplate>();
+    auto LT = std::make_unique<LateParsedTemplate>();
     LT->D = GetDecl(LateParsedTemplates[Idx++]);
 
     ModuleFile *F = getOwningModuleFile(LT->D);