[LibTooling] Fix unneeded use of unique_ptr where shared_ptr is expected.

[ymandel]

Summary

This fixes a few places in the Stencil implementation where a unique_ptr is created at a callsite that expects shared_ptr. Since the former implicitly converts to the latter, the code compiles and runs correctly as is. But, there's no reason to involve unique_ptr -- the current code was leftover from a previous version in which unique_ptr was the expected type.

clang/lib/Tooling/Refactoring/Stencil.cpp

 #include "clang/AST/ASTTypeTraits.h"
 #include "clang/AST/Expr.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Tooling/Refactoring/SourceCode.h"
 #include "llvm/Support/Errc.h"
 #include <atomic>
+#include <memory>
 #include <string>
 
 using namespace clang;
 using namespace tooling;
 
 using ast_matchers::MatchFinder;
 using llvm::Error;
 
Stencil::eval(const MatchFinder::MatchResult &Match) const {
   std::string Result;
   for (const auto &Part : Parts)
     if (auto Err = Part.eval(Match, &Result))
       return std::move(Err);
   return Result;
 }
 
 StencilPart stencil::text(StringRef Text) {
-  return StencilPart(llvm::make_unique<RawText>(Text));
+  return StencilPart(std::make_shared<RawText>(Text));
 }
 
 StencilPart stencil::node(StringRef Id) {
-  return StencilPart(llvm::make_unique<NodeRef>(Id, SemiAssociation::Inferred));
+  return StencilPart(std::make_shared<NodeRef>(Id, SemiAssociation::Inferred));
 }
 
 StencilPart stencil::sNode(StringRef Id) {
-  return StencilPart(llvm::make_unique<NodeRef>(Id, SemiAssociation::Always));
+  return StencilPart(std::make_shared<NodeRef>(Id, SemiAssociation::Always));
 }
 
 StencilPart stencil::dPrint(StringRef Id) {
-  return StencilPart(llvm::make_unique<DebugPrintNodeOp>(Id));
+  return StencilPart(std::make_shared<DebugPrintNodeOp>(Id));
 }