LibC: Fix futex return value handling

userspace/libraries/LibC/semaphore.cpp

@@ -57,8 +57,11 @@ int sem_timedwait(sem_t* __restrict sem, const struct timespec* __restrict absti
 		}
 
 		const int op = FUTEX_WAIT | (sem->shared ? 0 : FUTEX_PRIVATE) | FUTEX_REALTIME;
-		if (futex(op, &sem->value, expected, abstime) == -1 && (errno == EINTR || errno == ETIMEDOUT))
+		if (const int err = futex(op, &sem->value, expected, abstime); err != EAGAIN)
+		{
+			errno = err;
 			return -1;
+		}
 	}
 }