Necessary on the unix port when running with sanitizers, as the newly
increased stack size can run all tests at N=5000 without raising
RuntimeError, and increasing N to fix this causes issues on other
configurations.
This way the test progressively builds a deeper data structure until it
fails with RuntimeError. This is theoretically slower, but not noticeably
so in reality.
Signed-off-by: Angus Gratton <angus@redyak.com.au>
Keeping all the stress related tests in one place makes it easier to
stress-test a given port, and to also not run such tests on ports that
can't handle them.