1.0.42.25: check parent-lambdas in defined-fun-functional

1.0.42.25: check parent-lambdas in defined-fun-functional

 * Fixes lp#308951.

 * REFERENCE-LEAF could gain access to a functional in a strange
   lexenv using DEFINED-FUN-FUNCTIONAL, messing up access to bindings.

   Don't return a functional if the current lexenvs parent-lambda chain
   does not hold the parent of the functional.

   Also provides a more elegant fix for MISC.320.