wip: cosmocc

[prenaux]

Description, Motivation and Context

Add the cosmocc toolset which enables building a portable exe that runs on all the main desktop platforms.

See: https://justine.lol/cosmopolitan/index.html

How Has This Been Tested?

Command line to run all the tests that I run locally:

./_run_ci.sh

Types Of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that causes existing functionality to change)
• Documentation (code docs, comments, or changes to the doc systems)
• Testing/Build (test coverage or the test/build subsystems themselves)
• Packaging (adds examples or modifies a release package)