Avoids this error message with CMake 3.10:
CMake Error: CMake was unable to find a build program corresponding to "Ninja".
CMAKE_MAKE_PROGRAM is not set. You probably need to select a different build tool.

Related changes is that pkg-config tool is found (/usr/bin/pkg-config).

This makes it possible to compile OpenCV with for instance ndk-r16

- eliminate CMake 3.5+ warnings
- removed usage of dropped "OPENCV_CAMERA_MODULES" variable
- partial support for Android NDK 11+

The Android NDK would be moving to Clang as its default compiler
in the future. This patch allows OpenCV to build with the default
c++_shared / c++_static

TEST=Builds OpenCV with -DANDROID_TOOLCHAIN_NAME=
aarch64-linux-android-clang3.6 -DANDROID_STL=c++_shared

Add Android HardFP support. Expose the "armeabi-v7a-hard with NEON"
ANDROID_ABI.

TEST= Add -DANDROID_NATIVE_API_LEVEL=21
-DANDROID_ABI="armeabi-v7a-hard with NEON"

to compile with hardfp. Checked the output of make verbose to
confirm -lm_hard is being linked. There are known test
failures but that can be fixed once this is in.

Original project: https://github.com/taka-no-me/android-cmake/
Revision: 5db45cfb87fec180b74963d3680dd60d4d8d8c3a
(cherry picked from commit c8150436)

Original project: https://github.com/taka-no-me/android-cmake/
Revision: 5db45cfb87fec180b74963d3680dd60d4d8d8c3a

It was actually acting as an additional argument, breaking the error message.

Merged android.toolchain.cmake from project
https://github.com/taka-no-me/android-cmake
commit: fd1f7055f8b7338644d58d9a2015a784dfa3a5ca

Order returned by CMake is unreliable but we need clang to go after gcc for
automatic toolchain selection.

Ticket #2426

It is needed because of explicit STL include paths.
Otherwise some standard headers (like fenv.h) can not not be correctly found by the compiler.