+Note [IdInfo on nested let-bindings]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Occasionally we want to preserve IdInfo on nested let bindings The one
+that came up was a NOINLINE pragma on a let-binding inside an INLINE
+function. The user (Duncan Coutts) really wanted the NOINLINE control
+to cross the separate compilation boundary.
+
+So a IfaceLetBndr keeps a trimmed-down list of IfaceIdInfo stuff.
+Currently we only actually retain InlinePragInfo, but in principle we could
+add strictness etc.
+
+