mountlist: use /proc/self/mountinfo when available
Use libmount to propagate device IDs provided by Linux in
/proc/self/mountinfo. This will give more accurate output when using df
in chroot'ed environments as the device IDs are not determined by stat()
which may be inaccurate within the chroot.
Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
12fac096ed