40ad8f1666
This is consistent with the other 'micro' modules and allows implementing additional features in Python via e.g. micropython-lib's sys. Note this is a breaking change (not backwards compatible) for ports which do not enable weak links, as "import sys" must now be replaced with "import usys".
This directory doesn't contain real tests, but code snippets to detect various interpreter features, which can't be/inconvenient to detecte by other means. Scripts here are executed by run-tests at the beginning of testsuite to decide what other test groups to run/exclude.