Remove add PG prefix from symbols that are already local

Summary: After discussion with Maksim, we decided to drop the lines
that add the PG prefix if the symbol is already local, since they
wouldn't be impacted by the way LLVM handles these symbols.

(cherry picked from FBD28109400)

bolt/llvm-flo.cpp

@@ -410,10 +410,6 @@ static void OptimizeFile(ELFObjectFileBase *File, const DataReader &DR) {
       unsigned LocalCount = 1;
       std::string LocalName = (*Name).str() + "/" + FileSymbolName + "/";
 
-      if ((*Name).startswith(BC->AsmInfo->getPrivateGlobalPrefix())) {
-        LocalName = "PG." + LocalName;
-      }
-
       while (BC->GlobalSymbols.find(LocalName + std::to_string(LocalCount)) !=
              BC->GlobalSymbols.end()) {
         ++LocalCount;