The minimal change is just dropping the compiler_builtins dep and feature, since those are no longer needed for dependencies of the standard library (the in-tree compiler_builtins gets added instead). The rustc-dep-of-std bit would still be needed though, so that may be worth keeping around if you think there is a chance this winds back up in std's graph.

Ah I see 👍 Since the library isn't currently a dependency of std I'll remove that feature too, but if it ever finds its way back there we can always re-add it.