more precise memcpy tt

[ZuseZ4]

Third arg is the size, and thus always an int.

[wsmoses]

This should already be assumed why is this needed

[ZuseZ4]

I was also surprised since I would have expected Enzyme core to handle this.
I had enzyme complaining about can not deduce type of memcpy in a specific case where I had given tt for the first two args (src and dst, both -1:ptr and -1:0 to -1:72 being float). So I added this and now it went away.
Let me see if I can reproduce it by undoing this pr.