Add a pmUnits structure init routine in the python pmapi wrapper
Add a pmUnits structure init routine in the python pmapi wrapper

Discovered while developing pmdagluster that because the bitfields
in this stucture are conditionally init'd (HAVE_BITFIELDS_LTOT) the
order in which the fields are default-initialised is not guaranteed
to match up with the order in which we pass the arguments in.

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