In north Texas, our summers can be punishing. When outdoor temperatures reach the high nineties, brick walls get very hot and they expand. They not only expand horizontally, they expand in all directions. This expansion can push the last few bricks closest to the end of the wall downwardly and horzontally putting enough pressure on the corner of a concrete slab to break off a triangular shaped corner. Likewise it is not necessary to patch this separated piece of concrete slab since it is likely not to remain if you did. If you are so inclined, be my guest. If you do patch it, allow enough room between the patch and the bricks for further expansion and you might be successful.