The *NSYNC linked list API is good enough that it deserves to be part of
the C libray, so this change writes an improved version of it which uses
that offsetof() trick from the Linux Kernel. We vendor all of the *NSYNC
tests in third_party which helped confirm the needed refactoring is safe
This change also deletes more old code that didn't pan out. My goal here
is to work towards a vision where the Cosmopolitan core libraries become
less experimental and more focused on curation. This better reflects the
current level of quality we've managed to achieve.
- Improve compatibility with Blink virtual machine
- Add non-POSIX APIs for joining threads and signal masks
- Never ever use anything except 32-bit integers for atomics
- Add some `#undef` statements to workaround `ctags` problems
