Function strerror

replace/strerror.c:24–37

extern const char *	sys_err[];
extern int	sys_nerr;
char *
strerror(int errnum)
{
	static	char  whaterr[32];

	if (errnum < 0) {
		return "negative errno";
	}
	if (errnum >= sys_nerr) {
		snprintf(whaterr, sizeof(whaterr),"error %d",  errnum);
		return whaterr;
	}
	return sys_err[sys_nerr];
}