systemd pmda: install $(CMDTARGET)
systemd pmda: install $(CMDTARGET)

Commit 8d0b3db3832 in release 3.9.4 removed pmda .so build all right,
but also accidentally removed the installation of the pmdasystemd
executable.  Put that back.  The qa/652 test correctly asserts the
existence of the pmda binary; perhaps leftovers a previous build gave
a false-positive result.

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