Packages the distutils stdlib module as a standalone package,
```
377K distutils.data
221K distutils.data.br
19K distutils.js
```
to reduce the minimal pyodide size.

Part of #1542 

This also,
 - adds documentation on what's supported or not in the stdlib
 - makes a few changes to `pyodide_build/buildall.py` to be able to add such stdlib packages as a dependency in other packages (which didn't work before). For instance, until there is a release with https://github.com/pypa/packaging/pull/396 micropip has a dependency on distutils.
Unvendor distutils. Packages the distutils stdlib module as a standalone package,
```
377K distutils.data
221K distutils.data.br
19K distutils.js
```
to reduce the minimal pyodide size.

Part of #1542 

This also,
 - adds documentation on what's supported or not in the stdlib
 - makes a few changes to `pyodide_build/buildall.py` to be able to add such stdlib packages as a dependency in other packages (which didn't work before). For instance, until there is a release with https://github.com/pypa/packaging/pull/396 micropip has a dependency on distutils.
package:
  name: imageio
  version: 2.9.0
source:
  sha256: 52ddbaeca2dccf53ba2d6dec5676ca7bc3b2403ef8b37f7da78b7654bb3e10f0
  url: https://files.pythonhosted.org/packages/c3/73/f37f428748c4f10a7991ac5bff00f113a34bcc0d0a78957d6e1cdc29a94e/imageio-2.9.0.tar.gz
  patches:
  - patches/setitup.patch
requirements:
  run:
  - numpy
  - pillow
test:
  imports:
  - imageio

package:
  name: imageio
  version: 2.9.0
source:
  sha256: 52ddbaeca2dccf53ba2d6dec5676ca7bc3b2403ef8b37f7da78b7654bb3e10f0
  url: https://files.pythonhosted.org/packages/c3/73/f37f428748c4f10a7991ac5bff00f113a34bcc0d0a78957d6e1cdc29a94e/imageio-2.9.0.tar.gz
  patches:
  - patches/setitup.patch
requirements:
  run:
  - numpy
  - pillow
test:
  imports:
  - imageio
