Passes forktest w. 2 CPUs

Maybe have sleep/wakeup races too

Primitive partitioned proc table, per core runq, and non-scalable stealing
Panics on two cores, but i should make more frequent checkpoints

does not affect line numbers

Variable declarations at top of function,
separate from initialization.

Use == 0 instead of ! for checking pointers.

Consistent spacing around {, *, casts.

Declare 0-parameter functions as (void) not ().

Integer valued functions return -1 on failure, 0 on success.

fix double iunlockput

usertest that passes too many arguments, break exec

delete most comments from bootother.S (since copy of bootasm.S)
ksegment() -> seginit()
move more stuff from main() to mainc()

Simplify allocuvm/deallocuvm to operate in a contiguous memory model.  This makes their interface match up better with proc->sz and also simplifies the callers (it even gets the main body of exec on one page).