functional-tests: Tweaks to process helpers
functional-tests: Tweaks to process helpers

Note the bug I found where if you send TERM to tracker-extract while it's
initialising, it hangs. I'll fix this in a separate commit.

hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker