[sanitizer] New attempt at using runtime checks for Android logging

Summary:
This is a second attempt after D40100 induced racey crashes with ASan
(due to `__android_log_write` and the `strncpy` interceptor on API >= 21).

This new version checks the runtime API level to be <= `ANDROID_KITKAT` for
the use  of `__android_log_write`, otherwise we use `syslog`, which should
conform with the previous behavior.

Unfortunately despite numerous efforts I couldn't reproduce the original
crashes in my environments so I couldn't test that the fix was actually
preventing crashes.

Reviewers: eugenis

Reviewed By: eugenis

Subscribers: llvm-commits, srhines, kubamracek

Differential Revision: https://reviews.llvm.org/D40149

llvm-svn: 318659