Auto merge of #136965 - jhpratt:rollup-bsnqvmf, r=jhpratt

Rollup of 8 pull requests

Successful merges:

 - #134999 (Add cygwin target.)
 - #136559 (Resolve named regions when reporting type test failures in NLL)
 - #136660 (Use a trait to enforce field validity for union fields + `unsafe` fields + `unsafe<>` binder types)
 - #136858 (Parallel-compiler-related cleanup)
 - #136881 (cg_llvm: Reduce visibility of all functions in the llvm module)
 - #136888 (Always perform discr read for never pattern in EUV)
 - #136948 (Split out the `extern_system_varargs` feature)
 - #136949 (Fix import in bench for wasm)

r? `@ghost`
`@rustbot` modify labels: rollup