[ORC-RT] Fix missing std::move.

This should fix the 'could-not-covert' error at wrapper_function_utils.h:128 in
https://lab.llvm.org/buildbot/#/builders/112/builds/7748.

compiler-rt/lib/orc/wrapper_function_utils.h

@@ -125,7 +125,7 @@ serializeViaSPSToWrapperFunctionResult(const ArgTs &...Args) {
   if (!SPSArgListT::serialize(OB, Args...))
     return make_error<StringError>(
         "Error serializing arguments to blob in call");
-  return Result;
+  return std::move(Result);
 }
 
 template <typename RetT> class WrapperFunctionHandlerCaller {