Make the page allocator use a free page list instead of a silly
linear search.

Add sys_vhangup() and stubs for send/rcv/sendto/recvfrom/shutdown.
We're making ready for real networking..

Remove nonworking extfs bitmap allocators. We'll have them in ext2.

[Original announcement below]

Patch 1 is essentially a performance-release, but it also contains some
other patches: Ross Biro's tcp-ip stubs are there (but not the tcpip
subdirectory: alpha-testers should know where to find that), as are the
ext-fs superblock cleanups. The first header-file patch by hlu is also
in there.

The resulting patch is pretty big - it's also not as cleaned up as I'd
like it to be.  The swapping/buffer-block handling heuristics are
better, but could still do with some tuning.  Also, the idle task in
this version doesn't do very much: it will be expanded to do some more
page-table calculations.

I will be unable to hack on linux for a couple of weeks (I'll still
answer mails, read the newsgroup and fix bugs, but no heavy-duty
hacking) due to some "circumstances beyond my control".  That probably
means that this patch is the last one for a while (three weeks) unless
some bad bugs show up.

                Linus