Include versioned Android target in bindgen clang args for NDK 30

[Copilot]

NDK 30 rejects unversioned Android triples in clang invocations. cargo-ndk was exporting bindgen clang args without the API-suffixed target, which could surface Unversioned target triples are not supported! in bindgen-driven builds.

• Bindgen target propagation

  • Updated build_env to include the existing versioned clang_target in BINDGEN_EXTRA_CLANG_ARGS_<triple>.
  • This aligns bindgen’s clang invocation with the same --target=<triple><api> already used for compiler/linker paths.

• Coverage for regression

  • Added a focused unit test asserting bindgen args include a versioned Android target for aarch64-linux-android.

let bindgen_args = format!(
    "{clang_target} --sysroot={} -I{}",
    cargo_ndk_sysroot_path.display(),
    extra_include
);

• Fixes Unversioned target triples are not supported! #216