[llvm] [gn build] Enable hwasan for aarch64 Android (PR #115219)

[Nico Weber via llvm-commits]

https://github.com/nico approved this pull request.

LG, but please wait with landing until http://45.33.8.238/ is passing on Linux again (I'll look tomorrow morning), and watch that bot after landing to make sure it cycles successfully.

(...hm, actually I'm not sure if it does android builds, so it cycling successfully maybe isn't more signal than just "this didn't break everything". But that's still worth checking.)

https://github.com/llvm/llvm-project/pull/115219