* mkdir: remove 3 lines in source code.
* mkfs_minix: save 32 bytes, remove 4 bugs.
* mkswap: save 64 bytes, remove 1 bug.
* mkdir: remove 3 lines in source code.
* mkfs_minix: save 32 bytes, remove 4 bugs.
* mkswap: save 64 bytes, remove 1 bug.