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: optlang
  version: 1.5.1

source:
  sha256: 102fe84cae9568983be6c0dd23d2bc3aa1ce01aa1448316f088d1c72fcc0248f
  url: https://files.pythonhosted.org/packages/63/4d/7c4da36e4939f76ca32d53c4a1e5df688f6cfe291ba0302e56d6d88f5583/optlang-1.5.1.tar.gz

requirements:
  run:
  - sympy
  - six
  - swiglpk

test:
  imports:
  - optlang
  - optlang.glpk_interface
  - optlang.symbolics

package:
  name: optlang
  version: 1.5.1

source:
  sha256: 102fe84cae9568983be6c0dd23d2bc3aa1ce01aa1448316f088d1c72fcc0248f
  url: https://files.pythonhosted.org/packages/63/4d/7c4da36e4939f76ca32d53c4a1e5df688f6cfe291ba0302e56d6d88f5583/optlang-1.5.1.tar.gz

requirements:
  run:
  - sympy
  - six
  - swiglpk

test:
  imports:
  - optlang
  - optlang.glpk_interface
  - optlang.symbolics
