nilfs2: add compat ioctl

The current FS_IOC_GETFLAGS/SETFLAGS/GETVERSION will fail if
application is 32 bit and kernel is 64 bit.

This issue is avoidable by adding compat_ioctl method.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

diff --cc fs/nilfs2/dir.c
Simple merge

diff --cc fs/nilfs2/file.c
Simple merge

diff --cc fs/nilfs2/ioctl.c
Simple merge

diff --cc fs/nilfs2/nilfs.h
Simple merge