Transforms: address some late comments

We already use the llvm namespace.  Remove the unnecessary prefix.  Use the
StringRef::equals method to compare with C strings rather than instantiating
std::strings.

Addresses late review comments from David Majnemer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221564 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/Passes.cpp

@@ -446,7 +446,7 @@ void TargetPassConfig::addPassesToHandleExceptions() {
 void TargetPassConfig::addCodeGenPrepare() {
   if (getOptLevel() != CodeGenOpt::None && !DisableCGP)
     addPass(createCodeGenPreparePass(TM));
-  addPass(llvm::createRewriteSymbolsPass());
+  addPass(createRewriteSymbolsPass());
 }
 
 /// Add common passes that perform LLVM IR to IR transforms in preparation for