Support downloading Android emulator system image on Linux aarch64

[rmartin16]

Changes

• Adds support to create an AVD on Linux for aarch64

Notes

• This was the final major issue I had from my experimentation in Add support for Raspberry Pi #449
  • There's still the need to add android.aapt2FromMavenOverride to the gradle.properties file....but that's manageable as a manual thing....especially since you've still gotta get a working Android SDK first
• The changenote is misc so as not to give the impression that Android on Linux for aarch64 works without quite a bit of prerequisite work

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[freakboy3742]

Seems like a fairly straightforward change; I'll have to take your word that it works.

To clarify what's happened here - is this a case of something changing on the Java/Android side, or was this just an easy-win configuration change that we missed when we added the architecture checks?

[rmartin16]

To clarify what's happened here - is this a case of something changing on the Java/Android side, or was this just an easy-win configuration change that we missed when we added the architecture checks?

More of an easy-change config win that I didn't include in #1360. At the time, I was still coming to grips with more of my current understanding of the Android SDK.....so, I left out this change at the time. Today, though, I added building an Android app to my "proto-buildbot" experiment and realized I felt more comfortable about adding this support for Linux on aarch64 now.