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.
ac_cv_file__dev_ptmx=no
ac_cv_file__dev_ptc=no
ac_cv_func_dlopen=yes
ac_cv_lib_socket_socket=no
ac_cv_header_linux_vm_sockets_h=yes
ac_cv_little_endian_double=yes
ax_cv_c_float_words_bigendian=no

ac_cv_file__dev_ptmx=no
ac_cv_file__dev_ptc=no
ac_cv_func_dlopen=yes
ac_cv_lib_socket_socket=no
ac_cv_header_linux_vm_sockets_h=yes
ac_cv_little_endian_double=yes
ax_cv_c_float_words_bigendian=no
