remove knowledge of defaultallocator_free_displaysurface from sdl.c

Let register_displayallocator hand over the old width/height to the new
allocator.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

sdl.c

@@ -872,10 +872,6 @@ void sdl_display_init(DisplayState *ds, int full_screen, int no_frame)
     da->resize_displaysurface = sdl_resize_displaysurface;
     da->free_displaysurface = sdl_free_displaysurface;
     if (register_displayallocator(ds, da) == da) {
-        DisplaySurface *surf;
-        surf = sdl_create_displaysurface(ds_get_width(ds), ds_get_height(ds));
-        defaultallocator_free_displaysurface(ds->surface);
-        ds->surface = surf;
         dpy_resize(ds);
     }
 

vl.c

@@ -2615,7 +2615,13 @@ DisplayState *get_displaystate(void)
 
 DisplayAllocator *register_displayallocator(DisplayState *ds, DisplayAllocator *da)
 {
-    if(ds->allocator ==  &default_allocator) ds->allocator = da;
+    if(ds->allocator ==  &default_allocator) {
+        DisplaySurface *surf;
+        surf = da->create_displaysurface(ds_get_width(ds), ds_get_height(ds));
+        defaultallocator_free_displaysurface(ds->surface);
+        ds->surface = surf;
+        ds->allocator = da;
+    }
     return ds->allocator;
 }