Rollup of 8 pull requests

[tgross35]

Successful merges:

• add asm_cfg: #[cfg(...)] within asm! #140367 (add asm_cfg: #[cfg(...)] within asm!)
• Make check-cfg diagnostics work in #[doc(cfg(..))] #140894 (Make check-cfg diagnostics work in #[doc(cfg(..))])
• gvn: bail out unavoidable non-ssa locals in repeat #141252 (gvn: bail out unavoidable non-ssa locals in repeat)
• rustdoc: use descriptive tooltip if doctest is conditionally ignored #141517 (rustdoc: use descriptive tooltip if doctest is conditionally ignored)
• Make two transmute-related MIR lints into HIR lint #141551 (Make two transmute-related MIR lints into HIR lint)
• ci: fix llvm test coverage #141591 (ci: fix llvm test coverage)
• Bump master stage0 compiler #141647 (Bump master stage0 compiler)
• Add Result::map_or_default and Option::map_or_default #141659 (Add Result::map_or_default and Option::map_or_default)

r? @ghost
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