MINOR: task: Rename run_queue and run_queue_cur counters

<run_queue> is used to track the number of task in the run queue and
<run_queue_cur> is a copy used for the reporting purpose. These counters has
been renamed, respectively, <tasks_run_queue> and <tasks_run_queue_cur>. So the
naming is consistent between tasks and applets.

[wt: needed for next fixes, backport to 1.7 and 1.6]
diff --git a/include/proto/stream.h b/include/proto/stream.h
index db23956..b439344 100644
--- a/include/proto/stream.h
+++ b/include/proto/stream.h
@@ -302,7 +302,7 @@
 	 */
 	avail = pool2_buffer->allocated - pool2_buffer->used - global.tune.reserved_bufs / 2;
 
-	if (avail > (int)run_queue)
+	if (avail > (int)tasks_run_queue)
 		__stream_offer_buffers(avail);
 }