sem: Restructure calculation of waiter count a little

Author: lhmouse

mcfgthread/sem.c

@@ -75,7 +75,7 @@ _MCF_sem_signal_some(_MCF_sem* sem, intptr_t value_add)
         return -2;  /* would overflow  */
 
       new = old;
-      wake_num = _MCF_minz(-(size_t) old.__value, (size_t) value_add) & (size_t) (old.__value >> (__MCF_PTR_BITS - 1));
+      wake_num = _MCF_minz(-(size_t) (old.__value & (old.__value >> (__MCF_PTR_BITS - 1))), (size_t) value_add);
       new.__value = old.__value + value_add;
     }
     while(!_MCF_atomic_cmpxchg_weak_pptr_rlx(sem, &old, &new));