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: statsmodels
  version: 0.9.0

source:
  url: https://files.pythonhosted.org/packages/67/68/eb3ec6ab61f97216c257edddb853cc174cd76ea44b365cf4adaedcd44482/statsmodels-0.9.0.tar.gz
  sha256: 6461f93a842c649922c2c9a9bc9d9c4834110b89de8c4af196a791ab8f42ba3b

build:
  ldflags: -L$(PYODIDE_ROOT)/packages/numpy/build/numpy-1.17.5/install/lib/python3.8/site-packages/numpy/core/lib/

requirements:
  run:
    - numpy
    - scipy
    - pandas
    - patsy

test:
  imports:
    - statsmodels

package:
  name: statsmodels
  version: 0.9.0

source:
  url: https://files.pythonhosted.org/packages/67/68/eb3ec6ab61f97216c257edddb853cc174cd76ea44b365cf4adaedcd44482/statsmodels-0.9.0.tar.gz
  sha256: 6461f93a842c649922c2c9a9bc9d9c4834110b89de8c4af196a791ab8f42ba3b

build:
  ldflags: -L$(PYODIDE_ROOT)/packages/numpy/build/numpy-1.17.5/install/lib/python3.8/site-packages/numpy/core/lib/

requirements:
  run:
    - distutils
    - numpy
    - scipy
    - pandas
    - patsy

test:
  imports:
    - statsmodels
