1.0.9.42: remove stale CALLS support

1.0.9.42: remove stale CALLS support

* Permutation vector code contained infrastructure for optimizing
  GF calls inside method bodies in a similar manner as slot accesses
  are optimized, but this support was never finished.

  While it would be nice to have it, right now clarity of the code
  seems like a higher priority -- it seems to be simple enough to
  reinstate when we want, and the end result is liable to be easier to
  understand.

* Add a big FIXME with a short explanation of the optimization and
  a pointer to this commit.