xfs_quota: add capabilities for use on non-XFS filesystems

xfs_quota: add capabilities for use on non-XFS filesystems

This patch allows xfs_quota to be used on ext4 for project quota
testing in xfstests.  It was based on work originally from Dave
Chinner. As a part of its support for foreign filesystems xfs_quota
is modified with a "-f" command line flag to enable select commands
on those filesystems.

This requires us to discriminate different filesystem types when
walking the fileystem table during argument processing as the table
is now populated with mounted non-XFS filesystems. We should only
select a foreign filesystem mount point if the "-f" flag is present
on the command line.

This patch also updates the usage and man page information
for the new CLI flag appropriately.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>