[polly] Replace report_fatal_error(std::string) uses with report_fatal_error(Twine)

As described on D111049, we're trying to remove the <string> dependency from error handling and replace uses of report_fatal_error(const std::string&) with the Twine() variant which can be forward declared.

GitOrigin-RevId: f1be391bed5332a4926f1007790f7bd02a9d4bfa
1 file changed