Building SDL_image_compact for UWP
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SDL_image_compact uses Visual Studio 2017 to build on Xbox One.

Dependencies
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Before building, download SDL2 via Hg:

hg clone http://hg.libsdl.org/SDL SDL2

Note that we're naming the SDL folder "SDL2" and not "SDL", "SDL-2.0.8", etc.

Compiling
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1. Build SDL2/VisualC-WinRT/UWP_VS2015/SDL-UWP.sln
2. Build SDL_image_compact/visualc-winrt/SDL_image.sln
3. Grab the output DLLs, ship it!
