M10: The rest of the toolchain

[tamnd]

Five weeks. Part X, everything around the core: Clang, MLIR, lld, LTO, ORC, the sanitizers and PGO. Eight lessons, each scoped honestly rather than pretending to cover a subject that is its own project.

Exit criterion. L01 states its ClangIR claims with a date and a verification command, and a Clang contributor confirms them.

Tasks

• L01 to L08
• The MLIR and ClangIR chapters, scoped and dated
• The cross link to the CPython internals JIT chapter in L06, written jointly with that project

Gates

• A Clang contributor confirms L01's dated claims
• L06 and the CPython internals JIT chapter agree with each other and each links to the other

ClangIR and MLIR are the two places where writing "this is experimental" without a date guarantees the sentence is wrong within a year. Both chapters carry a date and the command a reader can run to find out what their own build does.