Enable removal of UNIX lock files

[sbc100]

This avoids leaving orphan locks files around after we are done when them.

See https://github.com/emscripten-core/emscripten/pull/24035

Fixes: #31

[sbc100]

Please add tests 👍

I can add a test that confirm the that lock file is deleted.

Added a test the races mentioned do not pose a problem is harder. Even if we added some intense stress tests that right conditions for the race might not happen.

Hopefully the former is enough?

[saikishor]

@gaborbernat When can we expect this to be merged and released?

[gaborbernat]

I worry a little that I had to remove this workaround which was added in: #317.

I can't seem to find a way to keep both of these fixes in place.

Not until we address this.