Fix rendering occured unlimited if window size changed multiple

Fix rendering occured unlimited if window size changed multiple

To support multi window cases, dali-adaptor count how many times
the window resize event occured.

But in dali-core scene has only bool flag.

So if scene changed multiple times during 1 render time,
surface resized count never be reduced as zero.
So it will keep rendering unlimited.

This patch make we return the number of surface rect changed,
so dali-adaptor can control the scene changed count well.

Change-Id: I35d0bcef3ff33c67f106b276848a2b5a26ccc67c
Signed-off-by: Eunki, Hong <eunkiki.hong@samsung.com>