Stores the 64-bit value from lane
This intrinsic is provided for completeness and is equivalent to
*m = u64x2_extract_lane::<L>(v) (which doesn’t require
This intrinsic is unsafe because it takes a raw pointer as an argument, and the pointer must be valid to store 8 bytes to. Note that there is no alignment requirement on this pointer since this intrinsic performs a 1-aligned store.