if *debugGcc {
		os.Stderr.Write(stdout)
		os.Stderr.Write(stderr)
	}
	return string(stderr)
}

// runGcc runs the gcc command line args with stdin on standard input.
// If the command exits with a non-zero exit status, runGcc prints
// details about what was run and exits.
// Otherwise runGcc returns the data written to standard output and standard error.
// Note that for some of the uses we expect useful data back