Plus general recipe clean ups, while we're at it.
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Tested locally only for mutagen. Will fix if something breaks.
`requests_python39` will pop up in in the reports due to missing `chardet_python39`.
Nothing requires `requests_python39` on tree, so will remove that at some point.
* python3.8: bulk removal of now obsolete "_python38" packages.
Done via scripting. No functional change intended or expected.
Some manual tweaks will follow.
* python3.8: further manual tweaks after bulk-3.8-removal.
Unlike the previous commit with automated changes,
I've tested builds for *these* recipes in beta4 64 bits.
- Use loops to generate the package/version specific PROVIDES.
- Use version suffixes for the provided cmds, except for the ones
from the package for the default Python version (3.9 currently).
