CPack can't work with absolute paths.

- removed OpenCV_LIB_DIR* vars (they are broken and not required anymore)
- OpenCVConfig.cmake doesn't contain ANDROID/CUDA code if there is no such support
- removed OpenCV2_INCLUDE_DIRS_CONFIGCMAKE, merged into OpenCV_INCLUDE_DIRS_CONFIGCMAKE
- fix hard-coded relative paths for OpenCV_INSTALL_PATH
- removed OpenCV_TBB_ARCH
- switch OpenCVConfig.cmake into 2-level mode for Android SDK

Test launch script updated to run new tests as well.

Useful for debug purposes:
    cmake -DDEBUG_POST="ocv_cmake_dump_vars(CUDA)" .
    cmake -DCMAKE_PRE="ocv_cmake_dump_vars(\"OPENCL|opencl\")" .

related: #5845

cap_v4l is better maintained and generally the code is in
better shape than cap_libv4l.

- added new functions from core module: split, merge, add, sub, mul, div, ...
- added function replacement mechanism
- added example of HAL replacement library

OpenBSD needs m and pthread like Net- and FreeBSD.

fixed trailing whitespaces
renamed files *vaapi* to *va_intel*
changed names vaapi* to va_intel*

- IPP is disabled by default when compiler is mingw (couldn't make it
work)
- fixed some warnings
- fixed some `__GNUC__` version checks (for correctness and convenience)
- removed UTF-8 BOM from hough.cpp (fixes #5253)