Make `--enable-big-digits=30` the default

[brettcannon]

Any reason to not make this be automatic when wasm32 is set?

[emmatyping]

Yeah this would be a good thing to upstream to CPython.

[emmatyping]

We should also probably make --without-pymalloc and --with-ensurepip=no the default on WASM, I don't see either of those ever getting used.

[brettcannon]

Created #22 and #23 for --without-pymalloc and --with-ensurepip, respectively.

[tiran]

Before we hard-code --enable-big-digits=30 and --without-pymalloc in configure and include, I would first like to understand and document the reason for the settings.

--without-ensurepip is obvious for emscripten, though.

[brettcannon]

The explanation for that setting is given at https://github.com/pyodide/pyodide/blob/771693ff99c55f5292823d86a95702291cf08755/cpython/Makefile#L129-L135

[tiran]

Thanks, I missed the comment there.

Fixed in python/cpython#29887