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.
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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.