Handle absense of server unix domain socket file gracefully
Handle absense of server unix domain socket file gracefully

No point warning that we couldn't remove the file during the
server process shutdown if something has already removed it.
Also, switch to using thread safe message reporting routines
and platform-agnostic errno manipulation.

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