The frame pointer sanity check in NextStackFrame() was more restrictive than it is necessary. The frame pointer is used to load the saved link-register and the address for the next stack frame. So it only needs to be 8-byte aligned. The aarch64 ABI does not specify an alignment requirement for the frame point.

PiperOrigin-RevId: 463368519
Change-Id: I473e05181603288f14734fe29013900c7505e201