statfs/statfs02.c: cleanup

* Delete some useless commtents.
* Use static.
* Move the test body from main() to statfs_verify().
* Some cleanup.

Signed-off-by: Zeng Linggang <zenglg.jy@cn.fujitsu.com>
statfs/statfs02.c: Add ELOOP errno test

Signed-off-by: Zeng Linggang <zenglg.jy@cn.fujitsu.com>