Apply clang-tidy's performance-unnecessary-value-param to parts of clang.

No functionality change intended.

llvm-svn: 298443
diff --git a/clang/lib/Serialization/GeneratePCH.cpp b/clang/lib/Serialization/GeneratePCH.cpp
index 429ae8e..2e00765 100644
--- a/clang/lib/Serialization/GeneratePCH.cpp
+++ b/clang/lib/Serialization/GeneratePCH.cpp
@@ -27,11 +27,11 @@
     ArrayRef<std::shared_ptr<ModuleFileExtension>> Extensions,
     bool AllowASTWithErrors, bool IncludeTimestamps)
     : PP(PP), OutputFile(OutputFile), isysroot(isysroot.str()),
-      SemaPtr(nullptr), Buffer(Buffer), Stream(Buffer->Data),
-      Writer(Stream, Buffer->Data, PP.getPCMCache(), Extensions,
+      SemaPtr(nullptr), Buffer(std::move(Buffer)), Stream(this->Buffer->Data),
+      Writer(Stream, this->Buffer->Data, PP.getPCMCache(), Extensions,
              IncludeTimestamps),
       AllowASTWithErrors(AllowASTWithErrors) {
-  Buffer->IsComplete = false;
+  this->Buffer->IsComplete = false;
 }
 
 PCHGenerator::~PCHGenerator() {