Bring MAKE-FUNCTIONAL-FROM-TOPLEVEL-LAMBDA into closer alignment with
MAKE-XEP. Specifically, cross-link the underlying function and the
TL-XEP, and mark the TL-XEP for reanalysis.
Fixes lp#310173 and lp#384892:
* Show &REST arguments properly in backtraces.
* Better type-derivation of function result types when the
lambda-list is complex.