Fix warnings about unused variables.

Change-Id: I147ff8624faa98396d6c48801c41a731fd02ac10
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>

src/plugins/directshow/camera/dscameraservice.cpp

@@ -119,6 +119,7 @@ QMediaControl* DSCameraService::requestControl(const char *name)
 
 void DSCameraService::releaseControl(QMediaControl *control)
 {
+    Q_UNUSED(control)
    // Implemented as a singleton, so we do nothing.
 }
 

src/plugins/directshow/camera/dscamerasession.cpp

@@ -96,6 +96,8 @@ public:
 
     STDMETHODIMP SampleCB(double Time, IMediaSample *pSample)
     {
+        Q_UNUSED(Time)
+        Q_UNUSED(pSample)
         return E_NOTIMPL;
     }
 

src/plugins/directshow/camera/dsimagecapturecontrol.h

@@ -58,7 +58,7 @@ public:
     int capture(const QString &fileName);
 
     virtual QCameraImageCapture::DriveMode driveMode() const { return QCameraImageCapture::SingleImageCapture; }
-    virtual void setDriveMode(QCameraImageCapture::DriveMode mode) { }
+    virtual void setDriveMode(QCameraImageCapture::DriveMode mode) { Q_UNUSED(mode) }
 
     virtual void cancelCapture() {}
 

src/plugins/directshow/camera/dsvideowidgetcontrol.cpp

@@ -107,6 +107,7 @@ void DSVideoWidgetSurface::updateVideoRect()
 
 void DSVideoWidgetSurface::paint(QPainter *painter)
 {
+    Q_UNUSED(painter)
 }