lib: Add xfs fs detection

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

Define the old_linux_dirent structure.

Signed-off-by: Zeng Linggang <zenglg.jy@cn.fujitsu.com>
readdir/readdir21.c: add new error number testes

Add ENOENT and ENOTDIR error number testes for readdir(2)

Signed-off-by: Zeng Linggang <zenglg.jy@cn.fujitsu.com>
lib: Add SAFE_RMDIR()

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>