[llvm-objcopy] Remove unused internal helper function template makeStringError. NFC

[jhenderson]

LGTM.

[tkoeppe]

I'm afraid I don't have commit access; would one of you be able to commit this?

llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp

case FileFormat::Binary:
     return std::make_unique<BinaryWriter>(Obj, Out);
   case FileFormat::IHex:
     return std::make_unique<IHexWriter>(Obj, Out);
   default:
     return createELFWriter(Config, Obj, Out, OutputElfType);
   }
 }
 
-template <class... Ts>
-static Error makeStringError(std::error_code EC, const Twine &Msg,
-                             Ts &&...Args) {
-  std::string FullMsg = (EC.message() + ": " + Msg).str();
-  return createStringError(EC, FullMsg.c_str(), std::forward<Ts>(Args)...);
-}
-
 static Error dumpSectionToFile(StringRef SecName, StringRef Filename,
                                Object &Obj) {
   for (auto &Sec : Obj.sections()) {
     if (Sec.Name == SecName) {
       if (Sec.Type == SHT_NOBITS)
         return createStringError(object_error::parse_failed,
                                  "cannot dump section '%s': it has no contents",
                                  SecName.str().c_str());