CVE-2024-5171: heap buffer overflow in libaom

Integer overflow in libaom internal function imgallochelper can lead to heap buffer overflow. This function can be reached via 3 callers:

Calling aomimgalloc() with a large value of the dw, dh, or align parameter may result in integer overflows in the calculations of buffer sizes and offsets and some fields of the returned aomimaget struct may be invalid. Calling aomimgwrap() with a large value of the dw, dh, or align parameter may result in integer overflows in the calculations of buffer sizes and offsets and some fields of the returned aomimaget struct may be invalid. Calling aomimgallocwithborder() with a large value of the dw, dh, align, sizealign, or border parameter may result in integer overflows in the calculations of buffer sizes and offsets and some fields of the returned aomimaget struct may be invalid.