[CVS ci] interpreter->iglobals: a list of some interpreter internal PMCs

[Leopold Toetsch]

I have moved some interpreter variables (classname_hash, compreg_hash, 
Argv, Env) into one (SArray) list: interpreter->iglobals.
There access isn't time critical, so the extra indirection wont harm.
We probably also want a new opocde: C<iglobals> or similar to get items 
out of this list.
The C<compreg> opcode could then be written as:

  iglobals P0, .IGLOBALS_COMPREG_HASH
  set P1, P0["PASM"]
Accessing Argv (after P0 was globbered) or getting a hash of PMC types 
would be similar.

Comments welcome,
leo