[llvm] [Android] Drop workarounds for older Android API levels pre 9, 17 and 21 (PR #161911)

[Brad Smith via llvm-commits]

brad0 wrote:

> (i was surprised to see in some of the diff context here that there's still support for ubuntu's "jaunty" release from 2009, for example, but maybe there's a documented llvm ubuntu release support policy somewhere?)

I gc'd the ancient Ubuntu bits and added a note for SUSE.

https://github.com/llvm/llvm-project/pull/161911