aom-tools: Integer overflow in libaom internal function img_alloc_helper can lead toheap buffer overflow

Integer overflow in libaom internal function img_alloc_helper can lead toheap buffer overflow. This function can be reached via 3 callers: * Calling aom_img_alloc() with a large value of the d_w, d_h, or alignparameter may result in integer overflows in the calculations of buffersizes and offsets and some fields of the returned aom_image_t struct may beinvalid. * Calling aom_img_wrap() with a large value of the d_w, d_h, or alignparameter may result in integer overflows in the calculations of buffersizes and offsets and some fields of the returned aom_image_t struct may beinvalid. * Calling aom_img_alloc_with_border() with a large value of the d_w,d_h, align, size_align, or border parameter may result in integer overflowsin the calculations of buffer sizes and offsets and some fields of thereturned aom_image_t struct may be invalid.

Where it's fixed