test: improve filtering

test: improve filtering

Improve code for filtering test groups. Also, move reading binary
symbols into filtering stage, so that tests that are meant to be
skipped are never attempted to be executed in the first place.
Before running tests, print out any tests that were skipped because
they weren't compiled.

Cc: stable@dpdk.org
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>