1.0.30.35: turn SB-INTROSPECT into an ASDF system

1.0.30.35: turn SB-INTROSPECT into an ASDF system

 * I at least am starting to find myself having to insert

      (EVAL-WHEN (...) (REQUIRE :SB-INTROSPECT))

   in too many places. This may be a sign that things aught to be in
   SB-EXT instead, but ASDFication seems like a logical next step.

   ...arguably all contribs but ASDF itself should be ASDF systems.