PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VALUE (Ada RFC)

[Richard Kenner]

     This is wrong (as discussed before) and is likely the cause of PR21573
     (not VRP-related, the expanders for SWITCH_EXPR look at these
     attributes, too).  I'm not sure if it is safe to delete these
     assignment statmeents because TYPE_MIN_VALUE/TYPE_MAX_VALUE are used
     quite extensively throught GIGI.

Well, what *should* they be set to?  That is indeed setting them to the
minimum and maximum values as defined by the language.