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.
The original source files are missing some imports. gcc assumes implicit
function declaration, so the code compiles fine, but emscripten sets
 -Werror=implicit-function-declaration so it is a hard error.

--- a/BLAS/SRC/xerbla.c
+++ b/BLAS/SRC/xerbla.c
@@ -10,6 +10,8 @@
 		http://www.netlib.org/f2c/libf2c.zip
 */
 
+#include <stdio.h>
+
 #include "f2c.h"
 #include "blaswrap.h"

--- a/INSTALL/tstiee.c
+++ b/INSTALL/tstiee.c
@@ -10,6 +10,8 @@
 		http://www.netlib.org/f2c/libf2c.zip
 */
 
+#include <string.h>
+
 #include "f2c.h"
 #include "blaswrap.h"


The original source files are missing some imports. gcc assumes implicit
function declaration, so the code compiles fine, but emscripten sets
 -Werror=implicit-function-declaration so it is a hard error.

--- a/BLAS/SRC/xerbla.c
+++ b/BLAS/SRC/xerbla.c
@@ -10,6 +10,8 @@
 		http://www.netlib.org/f2c/libf2c.zip
 */
 
+#include <stdio.h>
+
 #include "f2c.h"
 #include "blaswrap.h"

--- a/INSTALL/tstiee.c
+++ b/INSTALL/tstiee.c
@@ -10,6 +10,8 @@
 		http://www.netlib.org/f2c/libf2c.zip
 */
 
+#include <string.h>
+
 #include "f2c.h"
 #include "blaswrap.h"

