(2.4) Backports from master branch (#7854)

Enable SSE optimization

Pdb file support was changed in CMake 2.8.12, support was added in CMake 3.1.0 to work around the problems created by the change introduced in CMake 2.8.12.

- Substituted HAVE_WINRT with WINRT
- Fixed compilation issues in ocl.cpp and parallel.cpp
- Fixed compiler issue for WP8: "C2678: binary '+' : no operator found which takes a left-hand - Fixed gitignore
- Added #ifdef HAVE_OPENCL to remove compiler warnings in ocl.cpp
- Used NO_GETENV similar to '3rdparty\libjpeg\jmemmgr.c;
- Added ole32.lib for core module (for WindowsStore 8.0 builds)
- Made OpenCV_ARCH aware of ARM
Signed-off-by: Maxim Kostin <v-maxkos@microsoft.com>

* cmake CMP0054 and CMP0045
* aarch64 build
* portable code options in PCH cmake
* some of gcc 4.9 warnings

(cherry picked from commit b75cbfde)

Conflicts:

	cmake/OpenCVModule.cmake

Allow to build samples via OpenCV binaries from distribution package
(find_package with OpenCV_DIR).

They're not listed in the documentation for the FindZLIB module,
so we shouldn't use them unless necessary.

for libpng added.

On Android memory is not guaranted to be aligned and applications often crash with BUSERROR