Give pending finalizers a chance to run before main finalizer test
Give pending finalizers a chance to run before main finalizer test

This avoids a rare problem where the pointer that is being tested is
already overwritten with garbage before we can read the final reference
count.

In the parent commit (1b017bee), this problem can be triggered by
running:

    TEST_OPTS='--seed=52965' bundle exec rake test:all

mvz/gir_ffi,mvz/gir_ffi,mvz/gir_ffi