So scale-amd64 can build lwIP again..

This have to do with implementation, not interface.  Removing these
unmasks the sharing on tlbflush_req, which is something we expected.
Luckily, it doesn't expose any other sharing.

Load indirect array on demand and flush only on iupdate.

This eliminates all reports of unexpected sharing except a few cases
of honest-to-goodness memory reuse.