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)