TAKE - quota tidyup

[Nathan Scott <nathans@snort.melbourne.sgi.com>]

Some minor tidyups to make the quota VFS change more palatable
(our quota VFS change allows any filesystem to manage quota on
their own - currently only XFS has such a need).

cheers.


Date:  Thu Aug 23 04:23:54 PDT 2001
Workarea:  snort.melbourne.sgi.com:/diskb/build4/nathans/base-linux-xfs

The following file(s) were checked into:
  bonnie.engr.sgi.com:/isms/slinx/2.4.x-xfs


Modid:  2.4.x-xfs:slinx:101363a
linux/include/linux/fs.h - 1.111
linux/fs/dquot.c - 1.30
linux/fs/xfs/linux/xfs_super.c - 1.134
	- rework the quotactl entry point into a specific filesystem - use
	  a vector in the quota_mount_options structure rather than the
	  super_operations one.

linux/fs/xfs/linux/xfs_linux.h - 1.52
	- don't need to make up a bogus errno for EWRONGFS - this is never
	  passed back to userspace and is in fact never even looked at in
	  the kernel.  so just equate it to EINVAL and be done with it.

linux/include/linux/xqm.h - 1.6
	- update the comments for XFS quotactl ops - and only define them
	  if we haven't got them from elsewhere already... ideally, we want
	  these to be coming from quota.h someday soon.