UnlockArena();
if (arenaLock) { PR_DestroyLock(arenaLock); arenaLock = NULL; }
PR_IMPLEMENT(void) PL_ArenaFinish(){    PLArena *a, *next;    LockArena();    for (a = arena_freelist; a; a = next) {        next = a->next;        PR_DELETE(a);    }    arena_freelist = NULL;    UnlockArena();}