clean up backtrace code

call sync with curproc, not &proc0

add definition for ability to produce a backtrace

add backtrace function

avoid simple_lock deadlocks with machine independent VM code (from hibler)

get initial pc correct

just use <vm/vm.h> for VM include files

need to protect simplelock from multiple includes

add simple locking primitives

avoid panic's on attempted open's of non-existent devices

lock.h moves to /sys/sys

put in request to unmount all filesystems when rebooting

more POSIX and ANSI compliance (from karels)

LONG_MIN and LONG_MAX need suffixes, and ULONG_MAX must either
be spelled in decimal, or suffixed.
From: Chris Torek <torek@BSDI.COM>

must use hex constants

fix includes for new locking

btodb and dbtob need to work with 64-bit numbers (from karels)

fix external declarations to match prototyped return types

rather than passing sy_narg around, pass sy_argsize

allow swapping on sd1b and sd2b

turn off ISO networking

add ISO and CCITT opts, vn pdev. add NS option and cd pdev, commented out.

add NS and CCITT options, cd and vn pseudo-devs. (all commented out)

ioctl cmd arg is u_long, strategy returns void.

signal handler code is u_long, pull in vm_extern.h and fix grow() args.