Remove mknod(1) from sbase

mknod(1) is not POSIX and it is not portable so it should be
in ubase instead of sbase.

mknod.c

@@ -1,43 +0,0 @@
-/* See LICENSE file for copyright and license details. */
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <string.h>
-#include "util.h"
-
-static void
-usage(void)
-{
-	eprintf("usage: mknod [-m mode] name type major minor\n");
-}
-
-int
-main(int argc, char **argv)
-{
-	mode_t type, mode = 0644;
-	dev_t dev;
-
-	ARGBEGIN {
-	case 'm':
-		mode = estrtol(EARGF(usage()), 8);
-		break;
-	default:
-		usage();
-	} ARGEND;
-
-	if(argc != 4)
-		usage();
-
-	if(strlen(argv[1]) != 1 || !strchr("ucb", argv[1][0]))
-		eprintf("mknod: '%s': invalid type\n", argv[1]);
-	type = (argv[1][0] == 'b') ? S_IFBLK : S_IFCHR;
-
-	dev = makedev(estrtol(argv[2], 0), estrtol(argv[3], 0));
-
-	if(mknod(argv[0], type|mode, dev) == -1)
-		eprintf("mknod: '%s':", argv[0]);
-	return EXIT_SUCCESS;
-}