Android Gradle Plugin fails to find OpenCV from OpenCV_ROOT

[TimPushkin]

When I append a path to OpenCV into OpenCV_ROOT find_package doesn't consider this path even though it lists it in OpenCV_ROOT when CMake is run from Android Gradle Plugin. The same CMake script works fine on a usual CMake. The issue is described here in more detail.

The current solution is to iteratively set OpenCV_DIR to each path that was intended to be appended to OpenCV_ROOT and call find_package to determine if this path is correct. Firstly, this solution has a clear overhead, secondly, CMake adds each of the OpenCVConfig.cmake considered this way into build even if it doesn't correspond to a found package (and this results into another hack in BuildOpenCV.cmake where I have to patch OpenCVConfig-version.cmake insted of OpenCVConfig.cmake so it doesn't get added into the build).

[TimPushkin]

Seems like it can be fixed with set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE BOTH)