1.0.44.4: make MAKE-FUNCTIONAL-FROM-TOPLEVEL-LAMBDA build proper XEPs

 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.