The patch
430b397f6715d4d2f2569716c93fcd6292ace3dc ("[libc++] Granularize <type_traits> includes in <iterator>") missed some exports in the modulemap with became apparent in the reverting commit 12cb1cb3720d.
This fixes the issue by updating the modulemap. Note that the Clang ICE is not fixed by this change.
Note this looks wrong from libc++'s perspective. When this "solves" the issue we need to investigate why it fixes it; I think the export belongs to a different header.