Longstanding issues in the Android test runner means that compiler-rt unit
tests don't work on Android due to libc++ link-time issues. Looks like the
exported libc++ from the Android NDK is x86-64, even though it's part of the
ARM[64] toolchain... See similar measures for ASan and sanitizer-common that
disable unit tests for Android.
Should fully fix the Android bots (@vlad.tsyrklevich).