Errors should be handled in log mirroring goroutine

[LPowlett]

func mirrorLog (cmd/runmqserver/mirror.go:~77) uses an error channel errorChannel to pass back errors from the goroutine, but the returned error channel is never read, so errors from the go routine are not handled.

cmd/runmqserver/main.go:

// TODO: Use the error channel
_, err = mirrorSystemErrorLogs(ctx, &wg, mf)
^ Error channel