Fix perf2cfg unit tests and enable presubmit testing.

Test: atest --host perf2cfg_test
Test: As above but with an error planted in tests/test_parse.py,
  check that the test fails.
Test: Plant an error in test_parse.py and check that TH fails.
Test: cd system/extras/perf2cfg && atest
Test: m perf2cfg && perf2cfg -h
Change-Id: I9c0e569069e50dc7d879b5cf17d4a19212c7e922
3 files changed