mount, umount, swapon, fsck, lsblk, findmnt: ignore malformed lines

mount, umount, swapon, fsck, lsblk, findmnt: ignore malformed lines

The libmount provides way how to deal with parsing errors in fstab --
on error callback function is executed and according to the return
libmount manipulate with the malformed line, possible are three
states:

  1/ fatal error; all file ignored              (callback rc < 0)
  2/ recoverable error; malformed line ignored  (callback rc > 0)
  3/ ignore the error                           (callback rc == 0)

The 2/ is the default if no callback specified.

Unfortunately our utils uses 3/. The correct way is to use 2/.

Signed-off-by: Karel Zak <kzak@redhat.com>