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

[Nikita Popov via llvm-commits]

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

LGTM

> (github n00b asks: i see you updated the first comment on the conversation tab in a way that addresses @nikic's question, but do you need to do the commit message on the patch too? i think the answer is no, because github replaces that commit message at "squash and merge" time? otherwise lgtm.)

Only the PR description matters.

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