[clang] [Android] Drop workarounds for older Android API levels pre 23 (PR #161893)

[Brad Smith via cfe-commits]

brad0 wrote:

> thanks! btw, if you're looking for questionable android-themed bullshit to remove, i noticed the other day that the sanitizers are full of
> 
> ```
> #  if SANITIZER_LINUX && !SANITIZER_ANDROID
> ```
> 
> cruft that seems to date from before our team took over the ndk, so i suspect it's just "this didn't compile with linux 2.6-era headers, but the hackery is long obsolete"?

@enh-google Thanks. So far I had been mainly looking for instances of isAndroidVersionLT().

https://github.com/llvm/llvm-project/pull/161893