[9fans] minor kernel bug

[Yoann Padioleau]

Hi,

Here is a patch for tasklock.c:

int
lock(Lock *l)
{
        int i;
        ulong pc;

        pc = getcallerpc(&l);

        lockstats.locks++;
        if(up)
                inccnt(&up->nlocks);    /* prevent being scheded */
        if(tas(&l->key) == 0){
                if(up)
                        up->lastlock = l;
                l->pc = pc;
                l->p = up;
                l->isilock = 0;
+               l->m = MACHP(m->machno);
...
                return 0;
        }

we do that in ilock() and canlock() so it's a bug I think to not do it also in 
lock().
The field is only used in iprintcanlock which use canlock(), not lock(), so this
if fine, but for consistency it would be better to also do it in lock() no?