BUF/BIO cleanup 2/99:

BUF/BIO cleanup 2/99:

Localise buffer queue information into kern/vfs_bio.c, it should not be
messed with outside of the named file.  Convert the QUEUE_* #defines
into enum bufq_type, prefix the names with 'B'.  The change to initpbuf()
is acceptable since they are a hack anyway, not to mention that

Move vfs_bufstats() from kern/vfs_syscalls.c into kern/vfs_bio.c since
that's where it should really belong, atleast till its use is cleaned.

Move bufqueues extern from sys/buf.h into kern/vfs_bio.c as it shouldn't
be messed with by anything else.  It was only sitting in sys/buf.h
because of vfs_bufstats().

Note the change to initpbuf() is acceptable since they are a hack anyway,
not to mention that the said function and friends should probably reside
in kern/vfs_bio.c.