OpenCV_4.2.0/opencv-4.2.0/3rdparty/cpufeatures/README.md

The Android NDK provides a small library named cpufeatures that your app can use at runtime to detect the target device's CPU family and the optional features it supports. It is designed to work as-is on all official Android platform versions.

https://developer.android.com/ndk/guides/cpu-features.html