libpcp: fix memory leak in pmSetProgname
libpcp: fix memory leak in pmSetProgname

Causing QA fallout here, so drop for now while we
discuss this further (I'm not a fan of adding new
valgrind leak reports for PMAPI developers).

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