And that have been causing failures on Travis jobs, due to limited
on unreliable amount of resources present.

This is the full list of tests that won't be run anymore on Travis,
only on `make check-full`:

  selftests.functional.test_basic.RunnerOperationTest.test_early_latest_result
  selftests.functional.test_basic.RunnerSimpleTest.test_kill_stopped_sleep
  selftests.functional.test_interrupt.InterruptTest.test_well_behaved_sigint
  selftests.functional.test_interrupt.InterruptTest.test_well_behaved_sigterm
  selftests.functional.test_loader.LoaderTestFunctional.test_simple_using_main
  selftests.functional.test_loader.LoaderTestFunctional.test_sleep_a_lot
Signed-off-by: NCleber Rosa <crosa@redhat.com>