Eliminate unnecessary parts of mmu.h.

Add cons_puts for cleaner output.

(Fd_reference sounds like it might just return the ref count.)

Also remove all calls to memcpy in favor of
memmove, which has defined semantics when
the ranges overlap.  The fact that memcpy was
working in console.c to scroll the screen is not
guaranteed by all implementations.

Removed cli and sti stack in favor of tracking
number of locks held on each CPU and explicit
conditionals in spinlock.c.

They had been returning 0 on error, 1 on success, but all the callers
were checking for return value < 0.

wakeup1() assumes you hold proc_table_lock
sleep(chan, lock) provides atomic sleep-and-release to wait for condition
ugly code in swtch/scheduler to implement new sleep
fix lots of bugs in pipes, wait, and exit
fix bugs if timer interrupt goes off in schedule()
console locks per line, not per byte

exit had acquire where I meant release
swtch now checks that you hold no locks

nesting cli/sti: release shouldn't always enable interrupts
separate setup of lapic from starting of other cpus, so cpu() works earlier
flag to disable locking in console output
make locks work even when curproc==0
(still crashes in clock interrupt)