RFR(XS): 8133599: Unsafe.getAndSetObject() is no longer intrinsified by c2

[Roland Westrelin]

> Fix looks good, but what's the point for bounds-checking the $id anyway?
> Let the "default" clause in switch(id) to handle "return false",
> assuming no library-compiler-inline intrinsics appear in switch?

Thanks for looking at this, Aleksey. I guess bound checking the id is a
bit faster than going through the switch and maybe less error prone.

Roland.