Auto merge of #116123 - joboet:rewrite_native_tls, r=m-ou-se

Rewrite native thread-local storage

(part of #110897)

The current native thread-local storage implementation has become quite messy, uses indescriptive names and unnecessarily adds code to the macro expansion. This PR tries to fix that by using a new implementation that also allows more layout optimizations and potentially increases performance by eliminating unnecessary TLS accesses.

This does not change the recursive initialization behaviour I described in [this comment](rust-lang/rust#110897 (comment)), so it should be a library-only change. Changing that behaviour should be quite easy now, however.

r? `@m-ou-se`
`@rustbot` label +T-libs

Author: bors