Don't include the file system ID in the output of `mount -v' if it

Don't include the file system ID in the output of `mount -v' if it
is all zeros. The kernel now consistently zeroes FSIDs for non-root
users, so there's no point in printing these.

Also fix a number of compiler warnings, including two real bugs:
- a bracket placement bug caused `mount -t ufs localhost:/foo /mnt'
  to override the `-t ufs' specification and use mount_nfs.
- an unitialised variable was used instead of _PATH_SYSPATH when
  warning that the mount_* program cound not be found.

Submitted by:	Rudolf Cejka <cejkar@fit.vutbr.cz> (FSID part)
Approved by:	re (scottl)