build: FreeBSD build fix for 10.2 with dtrace probes auto-enabled
build: FreeBSD build fix for 10.2 with dtrace probes auto-enabled

It seems FreeBSD needs to use the Solaris mode of running dtrace
helper tool - otherwise build failure results.

wuliming/pcp,aeg-aeg/pcpfans,wuliming/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,aeg-aeg/pcpfans,aeg-aeg/pcpfans,wuliming/pcp,wuliming/pcp,aeg-aeg/pcpfans,wuliming/pcp,wuliming/pcp,aeg-aeg/pcpfans,adfernandes/pcp,adfernandes/pcp,aeg-aeg/pcpfans,wuliming/pcp,wuliming/pcp,aeg-aeg/pcpfans,adfernandes/pcp,aeg-aeg/pcpfans,adfernandes/pcp