qa/578: change acceptable range for openfds change
qa/578: change acceptable range for openfds change

Since the pmcd.openfds is supposed to be montonic increasing,
and the number of open files is a bit non-deterministic due
to DSO changes, parallel connections on sockets, IPC to PMDAs,
etc., so change the acceptable range for changes to be (0,+4).

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