Properly handle the case where QtWidgets is not available.

It does use a config test for now, just to make it clearer.  The Mac
backend currently requires widgets, but most of the others should work
without it (just not supporting QVideoWidget/WindowControl).

The QVideoDeviceControl interface was modified to remove the QIcon
usage - it was never implemented.

Unfortunately even the QML examples need widgets for the wrapper
application, and will need to be ported to QtGui based wrapper.

Change-Id: I8a55ad5cf09ab51749510bf16f49de0bd3f0bcdb
Reviewed-by: Ling Hu <ling.hu@nokia.com>

src/plugins/wmf/player/player.pri

@@ -24,7 +24,7 @@ SOURCES += \
     $$PWD/mfaudioendpointcontrol.cpp \
     $$PWD/mfmetadatacontrol.cpp
 
-!simulator {
+contains(config_test_widgets, yes):!simulator {
     HEADERS += $$PWD/evr9videowindowcontrol.h
     SOURCES += $$PWD/evr9videowindowcontrol.cpp
 }