Download SDL 2.0 source code from http://libsdl.org/ and extract here.

Special notes for Windows RT versions:
To make the screen shot function work properly, you need to modify the project files within the 
VisualC-WinRT directory (including SDL-WinPhone81.vcxproj, SDL-WinRT81.vcxproj & SDL-UWP.vcxproj)
by manually place the library file 'sdlpal.common.lib' before the 'msvcrt[d].lib'. This work can 
be done by adding the following LINK options:

"sdlpal.common.lib" "vccorlib[d].lib" "msvcrt[d].lib" /NODEFAULTLIB:"vccorlib[d].lib" /NODEFAULTLIB:"msvcrt[d].lib"

Note the the optional 'd' postfix is used only in debug builds. This work can also be done through
the Visual Studio's GUI.