Subsurf: Optimize edge drawing, now it uses VBOs.

Also the refactor exposed an error where we requested too much
memory from the video memory in general for all mesh types.

Now we are back to normal :)

source/blender/gpu/GPU_buffers.h

@@ -124,6 +124,10 @@ typedef struct GPUDrawObject {
 	unsigned int loose_edge_offset;
 	unsigned int tot_loose_edge_drawn;
 	unsigned int tot_edge_drawn;
+
+	/* for subsurf, offset where drawing of interior edges starts */
+	unsigned int interior_offset;
+	unsigned int totinterior;
 } GPUDrawObject;
 
 /* currently unused */