Update the pmdasimple sample code to clarify the fetch callback
Update the pmdasimple sample code to clarify the fetch callback

Also removes an opportunity to use an uninitialised times() list,
which results in an exception and associated badness.

adfernandes/pcp,prasincs/pcp,edwardt/pcp,tjanez/pcp,andyvand/cygpcpfans,tjanez/pcp,wuliming/pcp,prasincs/pcp,mbaldessari/pcp,adfernandes/pcp,tjanez/pcp,aeg-aeg/pcpfans,wuliming/pcp,mbaldessari/pcp,prasincs/pcp,edwardt/pcp,tjanez/pcp,prasincs/pcp,edwardt/pcp,aeg-aeg/pcpfans,prasincs/pcp,aeg-aeg/pcpfans,tjanez/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,wuliming/pcp,adfernandes/pcp,mbaldessari/pcp,wuliming/pcp,mbaldessari/pcp,edwardt/pcp,wuliming/pcp,wuliming/pcp,edwardt/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,adfernandes/pcp,andyvand/cygpcpfans,prasincs/pcp,andyvand/cygpcpfans,wuliming/pcp,tjanez/pcp,mbaldessari/pcp,edwardt/pcp,adfernandes/pcp,wuliming/pcp,prasincs/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,aeg-aeg/pcpfans,edwardt/pcp,mbaldessari/pcp,adfernandes/pcp,adfernandes/pcp,prasincs/pcp,adfernandes/pcp,tjanez/pcp,aeg-aeg/pcpfans,edwardt/pcp,tjanez/pcp,andyvand/cygpcpfans,andyvand/cygpcpfans