Rename loop unrolling and loop vectorizer metadata to have a common prefix.

[LLVM part]

These patches rename the loop unrolling and loop vectorizer metadata
such that they have a common 'llvm.loop.' prefix.  Metadata name
changes:

llvm.vectorizer.* => llvm.loop.vectorizer.*
llvm.loopunroll.* => llvm.loop.unroll.*

This was a suggestion from an earlier review
(http://reviews.llvm.org/D4090) which added the loop unrolling
metadata. 

Patch by Mark Heffernan.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211710 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AsmParser/LLParser.cpp

@@ -518,6 +518,7 @@ bool LLParser::ParseNamedGlobal() {
 bool LLParser::ParseMDString(MDString *&Result) {
   std::string Str;
   if (ParseStringConstant(Str)) return true;
+  llvm::UpgradeMDStringConstant(Str);
   Result = MDString::get(Context, Str);
   return false;
 }