src/libpcp_pmda/src/queues.c: cleanup the diagnostic reporting
src/libpcp_pmda/src/queues.c: cleanup the diagnostic reporting

wuliming/pcp,wuliming/pcp,adfernandes/pcp,wuliming/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,wuliming/pcp,adfernandes/pcp,adfernandes/pcp,wuliming/pcp,adfernandes/pcp,wuliming/pcp,adfernandes/pcp,wuliming/pcp,wuliming/pcp