VFS gets "permission()" virtual function.

[Original announcement below]

Still no 1.0 - I have had a couple of reports of problems, so I'll make
yet another 0.99 release.  The diffs (against 0.99.2) and complete
source can be found at nic.funet.fi: pub/OS/Linux/PEOPLE/Linus as usual,
and will probably show up at the other sites pretty soon.

0.99.3 contains no real new features, but the diffs are pretty big
anyway (100kB+ compressed): various things have moved around a bit and
there are a lot of minor changes.  The changes include (but are not
limited to):

 - the math emulator code now also understands the unofficial codes (in
   case somebody followed the ML math emulator thread).  I'd be
   interested to hear whether ML now works with the emulator.
 - various SCSI driver changes
 - some re-organization of the tty open/close code to remove a few race
   conditions.
 - interrupt handling rewrites (two-level interrupt code cleanups)
 - the serial drivers are tytso's alpha-drivers: they aren't quite
   completed, but as they need the interrupt handling patches to get
   ready, this is probably the least traumatic way of doing it.
 - some more minor keyboard driver changes (mostly taking advantage of
   the two-level interrupts)

+ a lot of other minor changes.  I once more hope people will try it
out, and report any problems or successes to me.

Known problems:
 - there seems to be something weird going on in the ST-0x driver with
   some scsi disks.
 - tcp/ip is reportedly still not quite stable, and I can't even test it
   out.

NOTE! The DMA functions have changed for the high DMA channels - all DMA
functions now take their arguments as the number of bytes instead of the
old way of using bytes for ch 0-3 and words for ch 5-7.  This might lead
to problems with the SoundBlaster driver, which may need editing.

                Linus