[regression] Linker warnings when building Miri on macOS

Since recently, Miri shows linker warnings when when building on macOS:

  warning: linker stderr: ''+zcm' is not a recognized feature for this target (ignoring feature)
           '+zcz' is not a recognized feature for this target (ignoring feature)
           +zcm' is not a recognized feature for this target (ignoring feature)
           '+zcz' is not a recognized feature for this target (ignoring feature)
           '+zcm' is not a recognized feature for this target (ignoring feature)
           '+zcz' is not a recognized feature for this target (ignoring feature)
           '+zcm' is not a recognized feature for this target (ignoring feature)
           '+zcz' is not a recognized feature for this target (ignoring feature)
           '+zcm' is not a recognized feature for this target (ignoring feature)
           '+zcz' is not a recognized feature for this target (ignoring feature)
...

Miri regression range: https://github.com/rust-lang/miri/compare/3807a616c9bc253240e6273045aa69ac7fcc2f0c...4fbd74609f426a0cc8f1882141eb5080fb3f14a2
Rustc regression range: https://github.com/rust-lang/rust/compare/73dc9167f1cd099e525c9ade2e068d1907b78564...7218ebe93668f51a94a572b690c433dfdbdc2c3d

Reproduce a Miri build on macOS and inspect the changes in the linked Miri and Rustc regression ranges first. Compare the relevant target and linker configuration across those ranges; done means the macOS build no longer emits the unrecognized +zcm and +zcz feature warnings.