Change `vm-kernel-precomp-android-release-arm` to use x64 gen_snapshot to produce 32-bit arm

[mkustermann]

As mentioned by @sjindel-google , this is what flutter does atm:

examples/flutter_gallery % flutter build aot --release --target-platform=android-arm -v
...
../../bin/cache/artifacts/engine/android-arm-release/linux-x64/gen_snapshot --causal_async_stacks --deterministic --snapshot_kind=app-aot-elf

examples/flutter_gallery % file ../../bin/cache/artifacts/engine/android-arm-release/linux-x64/gen_snapshot 
../../bin/cache/artifacts/engine/android-arm-release/linux-x64/gen_snapshot: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[xxHash]=c58929559abff580, stripped

[mkustermann]

@whesse / @athomas Could you look into this?

[whesse]

Looked at the build files with sjindel. Didn't find any obvious solutions, don't know what determines architecture. Neither of us are familiar with them, or how they work. Suggest asking zra or other MTV people who have written them.

[mkustermann]

It should be just figuring out what changes to build.py and gn.py and maybe the GN files to make to make it work for android.

Samir will do it :)

[mkustermann]

@sjindel-google Can this be closed now?