xp_err
xp_err(1, __LINE__, "fork");
xp_err(1, __LINE__, "read(i=%d)", i);
xp_err(1, __LINE__, "write(i=%d)", i);
xp_err(1, __LINE__, "sysctl kern.osrevision");
xp_err(1, __LINE__, "rump_or_open");
xp_err(1, __LINE__, "open %s", devaudioctl);
xp_err(1, __LINE__, "AUDIO_GETPROPS");
xp_err(1, __LINE__, "AUDIO_GETDEV");
void xp_err(int, int, const char *, ...) __printflike(3, 4) __dead;