rmdir/rmdir02.c: cleanup

Delete some useless comments.
Use some SAFE_* macros.
Move the test body from main() to rmdir_verify().

Signed-off-by: Xing Gu <gux.fnst@cn.fujitsu.com>
rmdir/rmdir02.c: add ELOOP, EROFS and EBUSY error value tests

Signed-off-by: Xing Gu <gux.fnst@cn.fujitsu.com>
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>