pyoxidizer: add user-site to `sys.path` on Windows This is a port of 53221078e0de to Windows to allow pip-installed extensions to be loaded without specifying a path. It's a major headache to have an hg.exe on `PATH` that needs to have the path to the extensions specified, because WSL doesn't see the same path. This is only for Windows for now, to match the currently shipping py2 behavior. There is a better solution with using the `site` package, but this needs support in PyOxidizer[1]. [1] https://github.com/indygreg/PyOxidizer/issues/430 Differential Revision: https://phab.mercurial-scm.org/D11308