libpcp - fix bug in __pmUnparseHostSpec
libpcp - fix bug in __pmUnparseHostSpec

pmDupContext() was failing for local: and unix: contexts.

Root cause was incorrect values being return in these cases from
__pmUnparseHostSpec().

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