Fix android emulator darwin_arm64 select

[keith]

This fixes this condition printing a strange error if you try to run
these on macOS. In general this still doesn't work because of
#7069 but if we ever want to
support it this is a pre-requisite to supporting arm macs

[ted-xie]

Hi Keith,

Thank you for this PR! At a glance it looks pretty low-risk. It looks like this is related to compiling Android projects on M1 Macs. Do you know how we could validate this fix on our own M1 machines, and have you done the same test on your own machine? What bug did this PR solve? In general, some more documentation around the select would be helpful context for maintainers.

[keith]

Trying to run an emulator test on macOS will first fail with this:

ERROR: /private/var/tmp/_bazel_snowp/5f415e59f25252568cd030dfdb79d872/external/android_test_support/tools/android/emulated_devices/generic_phone/BUILD.bazel:43:12: Creating Android image for @android_test_support//tools/android/emulated_devices/generic_phone:android_28_x86 failed: missing input file 'external/androidsdk/emulator/qemu/darwin-x86_64/qemu-system-i386', owner: '@androidsdk//:emulator/qemu/darwin-x86_64/qemu-system-i386'

As I mentioned this doesn't make these tests fully work, but this error looked more like an infrastructure error than a behavior limitation to the person who hit it here, which confused them into thinking it was just a misconfiguration.

[ted-xie]

Thanks for the background. Overall looks good to me; I'll start importing this and let you know if there are any show stoppers.

[brentleyjones]

@bazel-io flag

[ckolli5]

@bazel-io fork 5.2.0