pmmgr: build fix for older g++
pmmgr: build fix for older g++

std::map::at turns out to be a c++11 facility.
Use the equivalent but wordier find()->second instead.

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