Allow debugger to be compiled without Ganesh

https://codereview.appspot.com/7311084/



git-svn-id: http://skia.googlecode.com/svn/trunk@7710 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/debugger/QT/SkDebuggerGUI.h b/debugger/QT/SkDebuggerGUI.h
index 4130e96..bb3d6ce 100644
--- a/debugger/QT/SkDebuggerGUI.h
+++ b/debugger/QT/SkDebuggerGUI.h
@@ -112,10 +112,12 @@
      */
     void actionDelete();
 
+#if SK_SUPPORT_GPU
     /**
         Toggles the visibility of the GL canvas widget.
      */
     void actionGLWidget(bool isToggled);
+#endif
 
     /**
         Toggles the visibility of the inspector widget.