qa/364: small filter changes
qa/364: small filter changes

- add extra unknown metrics for openbsd
- add proc.smaps.* for linux (not present for all kernels)
- tighten up the sed patterns in _filter_linux() and _filter()

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp