man/lscp.1: remove "experimental" from the description of FLG field

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
nilfs-utils: compile legacy {mount,umount}.nilfs2 with libselinux

SELinux context mount options were optional for the legacy version of
{mount,umount}.nilfs2.  This changes the default build configuration
so that they are built with selinux library unless --without-selinux
options is specified.  When we compile them with libmount, libselinux
is not used regardless of this because context mount options are
provided by libmount.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
nilfs-utils: add --with-libmount build option

The libmount build option of the current configure script is confusing
since it is provided as an --enable-<feature> style option.

This fixes the issue by adding --with-libmount configure option.  The
--enable-libmount option is still available for compatibility reason.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
lib/nilfs.c: add missing initializations of ioctl arguments

Some wrapper functions for ioctl APIs in libnilfs do not initialize
unused arguments passed to kernel space.  This is hurting
extensibility of these ioctls.  This fixes the issue.

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