pmcollectl: host name improvements
pmcollectl: host name improvements

- document the -h HOST option in --help usage()
- default to local: rather than localhost
- when creating archive folios (-f FILE option), use the
  pmGetContextHostName result consistently

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