Reset the members' call counts when resetting queue statistics.

This helps to prevent odd scenarios where a queue will claim to have
taken 0 calls, but the members appear to have taken a non-zero amount.

(closes issue #15068)
Reported by: sum
Patches:
      patchreset.patch uploaded by sum (license 766)
Tested by: sum



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@193349 65c4cc65-6c06-0410-ace0-fbb531ad65f3