The 17.1.6 Bazel migration dropped maudio's generate-bindings feature, so
the darwin addon shipped maudio-sys's Linux-shaped pregenerated miniaudio
bindings. Those bindings omit the MA_SUPPORT_COREAUDIO backend-state union
members that the macOS build of miniaudio.c actually contains, producing a
Rust/C ABI mismatch: capture callbacks saw zero channels and yielded no PCM.
Re-enable generate-bindings for apple targets only. Patch maudio-sys's build
script to branch on Cargo's TARGET rather than the build-script host, so a
macOS-hosted Linux/Windows cross-build keeps target-family pregenerated
bindings instead of incorrectly running Darwin bindgen. Repin the Bazel graph
to apply the patch and gate bindgen behind the apple target selects.
Fixes#6846
roboomp
fc4fb70232