Updated FAQ to include text produced by iOS when installing binary packages

[freakboy3742]

This commit adds a monkeypatch to distutils to disable the C compiler. This PR updates the FAQ to reference the message that will be generated.

Also adds the --prefer-binary flag when installing packages so that an older binary will be preferred to a more recent source package.

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[mhsmith]

--prefer-binary applies to all wheels, whether pure-Python or not. I've encountered some projects on PyPI which released pure-Python wheels for old versions, and then stopped for some reason and now only release sdists for new versions. In that case, --prefer-binary will prefer the old wheel over the newer sdist, which probably isn't what the user wants.

I worked around this by adding this patch to Chaquopy's copy of pip, which causes it to prefer only binary wheels, not pure-Python ones.

Unfortunately I didn't make a note of what packages this affected, so I don't know whether this is still necessary. --prefer-binary will get us 99% of the way there, so let's just go with it, and if it causes any problems we'll find out soon enough.