Change Details

[This part of flit explicitly supports self-hosting](https://flit.pypa.io/en/latest/bootstrap.html). Remove all BUILD_ and RUN_DEPENDS to allow this port to bootstrap other components needed to support PEP-517 packaging. Namely, this cannot depend on setuptools as setuptools itself will eventually bootstrap from this and other components, especially after distutils is removed. PEP-517 will be a paradigm shift in Uses/python.

[This part of flit explicitly supports self-hosting](https://flit.pypa.io/en/latest/bootstrap.html). Remove all BUILD_ and RUN_DEPENDS to allow this port to bootstrap other components needed to support PEP-517 packaging. Namely, this cannot depend on setuptools as latest setuptools (> 58) itself will eventually bootstrap from this and other components, especially after distutils is removed.

[This part of flit explicitly supports self-hosting](https://flit.pypa.io/en/latest/bootstrap.html). Remove all BUILD_ and RUN_DEPENDS to allow this port to bootstrap other components needed to support PEP-517 packaging. Namely, this cannot depend on setuptools as latest setuptools (> 58) itself will eventually bootstrap from this and other components, especially after distutils is removed. PEP-517 will be a paradigm shift in Uses/python.