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: astropy
  version: 3.2.3

source:
  url: https://pypi.io/packages/source/a/astropy/astropy-3.2.3.tar.gz
  sha256: 47f00816c2978fdd10f448c8f0337d6dca7b8cbeaab4bf272b5fd37cb4b890d3
  patches:
    - patches/fix_link_opts.patch

requirements:
  run:
    - numpy

test:
  imports:
    - astropy

package:
  name: astropy
  version: 3.2.3

source:
  url: https://pypi.io/packages/source/a/astropy/astropy-3.2.3.tar.gz
  sha256: 47f00816c2978fdd10f448c8f0337d6dca7b8cbeaab4bf272b5fd37cb4b890d3
  patches:
    - patches/fix_link_opts.patch

requirements:
  run:
    - distutils
    - numpy

test:
  imports:
    - astropy
