AdvMame4x and Normal4x
|Reported by:||SF/mbandsmer||Owned by:|
This fixes the pre-existing scale4x code and enables it for the SDL backend. Also provided is a trivial Normal4x scaler for comparison.
I also added the #define MAX_SCALER_REACH to make it clearer where in the code extra borders are required because of scalers which access surrounding pixels. (Before, an implied constant of 1 was used in several places.)
Ticket imported from: #1536248. Ticket imported from: patches/672.