[bazel][mac] Define toolchain for x64->arm64 cross-compilation
* Define the `clang_host_mac_x64_target_mac_arm64_toolchain` target
which is compatible with cpu:x86_64 for execution and cpu:arm64 for
target platform.
* Explicitly include the "aarch64-apple-darwin" toolchain for Rust
targets. The rust toolchain rules automatically generate
cross-compilation permutations based on included platforms.
* Update the third_party/vello GN action to specify the correct
host/platform toolchain based on GN args when invoking bazel.
Change-Id: I1f6ecd3b87418fc643921491149be3116db8e4ec
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/723296
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Arman Uguray <armansito@google.com>
5 files changed
