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/simulator/camera/simulatorvideoinputdevicecontrol.cpp

@@ -41,7 +41,6 @@
 
 #include "simulatorvideoinputdevicecontrol.h"
 
-#include <QtWidgets/QIcon>
 #include <QtCore/QDir>
 #include <QtCore/QDebug>
 #include <QtCore/QStringList>
@@ -77,12 +76,6 @@ QString QSimulatorVideoInputDeviceControl::deviceDescription(int index) const
     return mDescriptions[index];
 }
 
-QIcon QSimulatorVideoInputDeviceControl::deviceIcon(int index) const
-{
-    Q_UNUSED(index);
-    return QIcon();
-}
-
 int QSimulatorVideoInputDeviceControl::defaultDevice() const
 {
     if (mDevices.isEmpty())

src/plugins/simulator/camera/simulatorvideoinputdevicecontrol.h

@@ -61,7 +61,6 @@ public:
 
     QString deviceName(int index) const;
     QString deviceDescription(int index) const;
-    QIcon deviceIcon(int index) const;
 
     int defaultDevice() const;
     int selectedDevice() const;