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: libxslt
  version: 1.1.33

source:
  sha256: 8e36605144409df979cab43d835002f63988f3dc94d5d3537c12796db90e38c8
  url: http://xmlsoft.org/sources/libxslt-1.1.33.tar.gz

requirements:
  run:
    - libxml

build:
  library: true
  script: |
    emconfigure ./configure \
        CFLAGS="-fPIC" \
        --disable-dependency-tracking \
        --disable-shared \
        --without-python \
        --with-libxml-src="$PYODIDE_ROOT/packages/libxml/build/libxml2-2.9.10" \
        --without-crypto
    emmake make -j ${PYODIDE_JOBS:-3}

package:
  name: libxslt
  version: 1.1.33

source:
  sha256: 8e36605144409df979cab43d835002f63988f3dc94d5d3537c12796db90e38c8
  url: http://xmlsoft.org/sources/libxslt-1.1.33.tar.gz

requirements:
  run:
    - libxml

build:
  library: true
  script: |
    emconfigure ./configure \
        CFLAGS="-fPIC" \
        --disable-dependency-tracking \
        --disable-shared \
        --without-python \
        --with-libxml-src="$PYODIDE_ROOT/packages/libxml/build/libxml2-2.9.10" \
        --without-crypto
    emmake make -j ${PYODIDE_JOBS:-3}
