GRAPHICS: fix off-by-one errors when drawing a rounded rectangle

The code would create a rectangle of width+1 by weight+1, resulting
in buffer overflows when drawing at the bottom limit of a surface.

graphics/VectorRendererSpec.cpp

@@ -4140,9 +4140,9 @@ drawInteriorRoundedSquareAlg(int x1, int y1, int r, int w, int h, PixelType colo
 	rsq = r*r;
 
 	PixelType *ptr_tl = (PixelType *)Base::_activeSurface->getBasePtr(x1 + r, y1 + r);
-	PixelType *ptr_tr = (PixelType *)Base::_activeSurface->getBasePtr(x1 + w - r, y1 + r);
-	PixelType *ptr_bl = (PixelType *)Base::_activeSurface->getBasePtr(x1 + r, y1 + h - r);
-	PixelType *ptr_br = (PixelType *)Base::_activeSurface->getBasePtr(x1 + w - r, y1 + h - r);
+	PixelType *ptr_tr = (PixelType *)Base::_activeSurface->getBasePtr(x1 + w - 1 - r, y1 + r);
+	PixelType *ptr_bl = (PixelType *)Base::_activeSurface->getBasePtr(x1 + r, y1 + h - 1 - r);
+	PixelType *ptr_br = (PixelType *)Base::_activeSurface->getBasePtr(x1 + w - 1 - r, y1 + h - 1 - r);
 	PixelType *ptr_fill = (PixelType *)Base::_activeSurface->getBasePtr(x1, y1);
 
 	int short_h = h - 2 * r;
@@ -4214,7 +4214,7 @@ drawInteriorRoundedSquareAlg(int x1, int y1, int r, int w, int h, PixelType colo
 
 		ptr_fill += pitch * r;
 		while (short_h-- >= 0) {
-			colorFill<PixelType>(ptr_fill, ptr_fill + w + 1, color);
+			colorFill<PixelType>(ptr_fill, ptr_fill + w, color);
 			ptr_fill += pitch;
 		}
 	}