pyoxidizer: update to PyOxidizer 0.9
We were previously using a Git commit from a few days before the 0.8
release. This commit upgrades us to the just-released 0.9 release.
This required some Starlark changes due to backwards incompatible
changes.
Differential Revision: https://phab.mercurial-scm.org/D9228
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.