Fix Cycles unnecessary updates to camera in viewport render

Problem identified by Milan Jaros.

intern/cycles/blender/blender_camera.cpp

@@ -709,6 +709,10 @@ static void blender_camera_from_view(BlenderCamera *bcam,
 
   /* 3d view transform */
   bcam->matrix = transform_inverse(get_transform(b_rv3d.view_matrix()));
+
+  /* dimensions */
+  bcam->full_width = width;
+  bcam->full_height = height;
 }
 
 static void blender_camera_view_subset(BL::RenderEngine &b_engine,

intern/cycles/render/session.cpp

@@ -1003,7 +1003,7 @@ bool Session::update_scene()
   int height = tile_manager.state.buffer.full_height;
   int resolution = tile_manager.state.resolution_divider;
 
-  if (width != cam->width || height != cam->height) {
+  if (width != cam->width || height != cam->height || resolution != cam->resolution) {
     cam->width = width;
     cam->height = height;
     cam->resolution = resolution;