qmlglsink: fix compilation with Qt >= 5.5 on Windows
As of Qt >= 5.5, qmake do not link to opengl32 by default anymore. This commit adds opengl32.lib to the .pro file so that the plugin can be build using QtCreator on Windows.
As of Qt >= 5.5, qmake do not link to opengl32 by default anymore. This commit adds opengl32.lib to the .pro file so that the plugin can be build using QtCreator on Windows.