Fix linking problem when built with -no-opengl

When -no-opengl was used then it was not automatically pulling in the
needed Windows libraries as it was not loading opengl.prf to get them
from.

Change-Id: I9b73e5ee01da964a64c71b6261ff4ed98ce6f1a9
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>

src/plugins/wmf/wmf.pro

@@ -4,6 +4,9 @@ qtHaveModule(widgets) {
     QT += multimediawidgets-private
     DEFINES += HAVE_WIDGETS
 }
+win32:!qtHaveModule(opengl) {
+    LIBS_PRIVATE += -lgdi32 -luser32
+}
 
 PLUGIN_TYPE=mediaservice
 PLUGIN_CLASS_NAME = WMFServicePlugin