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.
Proper Freetype linking.

diff --git a/setupext.py b/setupext.py
--- a/setupext.py
+++ b/setupext.py
@@ -522,6 +522,9 @@ class FreeType(SetupPackage):
     name = "freetype"
 
     def add_flags(self, ext):
+        if "PYODIDE" in os.environ:
+            ext.libraries.append('freetype')
+            return
         ext.sources.insert(0, 'src/checkdep_freetype2.c')
         if options.get('system_freetype'):
             pkg_config_setup_extension(
-- 
2.20.1


Proper Freetype linking.

diff --git a/setupext.py b/setupext.py
--- a/setupext.py
+++ b/setupext.py
@@ -522,6 +522,9 @@ class FreeType(SetupPackage):
     name = "freetype"
 
     def add_flags(self, ext):
+        if "PYODIDE" in os.environ:
+            ext.libraries.append('freetype')
+            return
         ext.sources.insert(0, 'src/checkdep_freetype2.c')
         if options.get('system_freetype'):
             pkg_config_setup_extension(
-- 
2.20.1

