teach IR1-TRANSFORM-TYPE-PREDICATE about alien types

teach IR1-TRANSFORM-TYPE-PREDICATE about alien types

  Convert to ALIEN-VALUE-TYPEP (new function). Avoids both the need to do the
  whole type parsing rigamarole at runtime, and checking for lisp-rep-type.

  Need to do this as late in the game as possible, because after we convert to
  ALIEN-VALUE-TYPEP, the rest of the system stops understanding it as a type
  test. (We really should have some sort of annotation for this sort of stuff,
  so we could convert whenever.)