LU-9235 libcfs: don't dump stack if just touched

LU-9235 libcfs: don't dump stack if just touched

If some lc_watchdog was touched before lcw_dump_stack dumped
the stack of the thread, it should not dump it anymore for
the thread is verified to be active and no need to dump.

Change-Id: I8e4acc1793bb8458ee3b6dc73f2953670ed22896
Signed-off-by: Hongchao Zhang <hongchao.zhang@intel.com>
Reviewed-on: https://review.whamcloud.com/23162
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>