BUG/MEDIUM: mworker: fix several typos in mworker_cleantasks()

Commit 27f3fa5 ("BUG/MEDIUM: mworker: stop every tasks in the master")
used MAX_THREADS as a mask instead of MAX_THREADS_MASK to clean the
global run queue, and used rq_next (global variable) instead of next_rq.

Renamed next_rq as tmp_rq and next_wq as tmp_wq to avoid confusion.

No backport needed.
diff --git a/src/task.c b/src/task.c
index b9b8bd2..11a171d 100644
--- a/src/task.c
+++ b/src/task.c
@@ -476,41 +476,41 @@
 {
 	struct task *t;
 	int i;
-	struct eb32_node *next_wq = NULL;
-	struct eb32sc_node *next_rq = NULL;
+	struct eb32_node *tmp_wq = NULL;
+	struct eb32sc_node *tmp_rq = NULL;
 
 #ifdef USE_THREAD
 	/* cleanup the global run queue */
-	next_rq = eb32sc_first(&rqueue, MAX_THREADS);
-	while (next_rq) {
-		t = eb32sc_entry(next_rq, struct task, rq);
-		next_rq = eb32sc_next(rq_next, MAX_THREADS_MASK);
+	tmp_rq = eb32sc_first(&rqueue, MAX_THREADS_MASK);
+	while (tmp_rq) {
+		t = eb32sc_entry(tmp_rq, struct task, rq);
+		tmp_rq = eb32sc_next(tmp_rq, MAX_THREADS_MASK);
 		task_delete(t);
 		task_free(t);
 	}
 	/* cleanup the timers queue */
-	next_wq = eb32_first(&timers);
-	while (next_wq) {
-		t = eb32_entry(next_wq, struct task, wq);
-		next_wq = eb32_next(next_wq);
+	tmp_wq = eb32_first(&timers);
+	while (tmp_wq) {
+		t = eb32_entry(tmp_wq, struct task, wq);
+		tmp_wq = eb32_next(tmp_wq);
 		task_delete(t);
 		task_free(t);
 	}
 #endif
 	/* clean the per thread run queue */
 	for (i = 0; i < global.nbthread; i++) {
-		next_rq = eb32sc_first(&task_per_thread[i].rqueue, MAX_THREADS_MASK);
-		while (next_rq) {
-			t = eb32sc_entry(next_rq, struct task, rq);
-			next_rq = eb32sc_next(next_rq, MAX_THREADS_MASK);
+		tmp_rq = eb32sc_first(&task_per_thread[i].rqueue, MAX_THREADS_MASK);
+		while (tmp_rq) {
+			t = eb32sc_entry(tmp_rq, struct task, rq);
+			tmp_rq = eb32sc_next(tmp_rq, MAX_THREADS_MASK);
 			task_delete(t);
 			task_free(t);
 		}
 		/* cleanup the per thread timers queue */
-		next_wq = eb32_first(&task_per_thread[i].timers);
-		while (next_wq) {
-			t = eb32_entry(next_wq, struct task, wq);
-			next_wq = eb32_next(next_wq);
+		tmp_wq = eb32_first(&task_per_thread[i].timers);
+		while (tmp_wq) {
+			t = eb32_entry(tmp_wq, struct task, wq);
+			tmp_wq = eb32_next(tmp_wq);
 			task_delete(t);
 			task_free(t);
 		}