Like the Visual Studio 2010 builds, the install project needs to be split
into two, one for the WGL-only configs and another for the WGL+SDL
configs, so that the Cogl and Cogl-Pango DLLs and LIBs can be correctly
copied during the "install" stage, as the resulting DLLs for all configs
land in {Release|Debug}\{Win32|x64}\bin.
