!PARSE-VOP- helpers shouldn't become uninterned by !UNINTERN-INIT-ONLY-STUFF.

These functions aren't actually gc'able because PARSE-DEFINE-VOP, which isn't,
hangs on to the fdefns, so uninterning of the names was pointless and weird.
Speed up INFINITE-ERROR-PROTECT
Set REPL variables to NIL before saving a core.

*/**/***, etc. may hold onto garbage.
Simplify !DEF-PRIMITIVE-TYPE and !DEF-PRIMITIVE-TYPE-ALIAS