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]
6 files changed