Do not lock vm map in swapout_procs().

[kib]

Summary

Neither swapout_procs() nor swapout() access the map.

[kib]

Referencing vmspace is useless after vm_map is not accessed.

[alc]

Hmm. Do we still need to unlock and relock the process?

_PHOLD_LITE(p);
PROC_UNLOCK(p);
sx_sunlock(&allproc_lock);

PROC_LOCK(p);
if (p->p_lock != 1 || (p->p_flag & (P_STOPPED_SINGLE |
    P_TRACED | P_SYSTEM)) != 0)
        goto nextproc;