fix several locks that weren't updated right for new futex-based __lock

these could have caused memory corruption due to invalid accesses to
the next field. all should be fixed now; I found the errors with fgrep
-r '__lock(&', which is bogus since the argument should be an array.

src/thread/pthread_create.c

@@ -24,12 +24,12 @@ void pthread_exit(void *result)
 
 	__pthread_tsd_run_dtors();
 
-	__lock(&self->exitlock);
+	__lock(self->exitlock);
 
 	/* Mark this thread dead before decrementing count */
-	__lock(&self->killlock);
+	__lock(self->killlock);
 	self->dead = 1;
-	a_store(&self->killlock, 0);
+	__unlock(self->killlock);
 
 	do n = libc.threads_minus_1;
 	while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n);

src/thread/pthread_detach.c

@@ -3,9 +3,9 @@
 int pthread_detach(pthread_t t)
 {
 	/* Cannot detach a thread that's already exiting */
-	if (a_swap(&t->exitlock, 1))
+	if (a_swap(t->exitlock, 1))
 		return pthread_join(t, 0);
 	t->detached = 2;
-	a_store(&t->exitlock, 0);
+	__unlock(t->exitlock);
 	return 0;
 }

src/thread/pthread_kill.c

@@ -3,8 +3,8 @@
 int pthread_kill(pthread_t t, int sig)
 {
 	int r;
-	__lock(&t->killlock);
+	__lock(t->killlock);
 	r = t->dead ? ESRCH : -__syscall(SYS_tgkill, t->pid, t->tid, sig);
-	__unlock(&t->killlock);
+	__unlock(t->killlock);
 	return r;
 }