[compiler-rt] [sanitizer_common] Drop support for Android 5 (PR #145227)

[via llvm-commits]

enh-google wrote:

@emrekultursay @DanAlbert fyi

(it probably doesn't matter much in practice -- not least because devices this old are likely to be 32-bit, and arm32 debugging is pretty comprehensively broken already -- but note that this is slightly ahead of us... we're still working on moving to api 22 [or, more likely 23] as our minimium.)

https://github.com/llvm/llvm-project/pull/145227