extend.c:Parrot_call

Parrot_call() runs a Parrot subroutine, but it takes PMC arguments only 
and provides no return value.

If no one hollers, I'll replace this function with a more flexible set 
of functions that are wrappers to the *runops* functions in src/inter_run.c:

  void *        Parrot_call_sub_(interp, sub, signature, ...) [1]
  Parrot_Int    Parrot_call_sub_ret_int
  Parrot_Float  Parrot_call_sub_ret_float

  void *        Parrot_call_meth(interp, sub, object, meth, sig, ...)
  ...

The signature of the current Parrot_call is "vPPP..."

[1] return values covered: void, Parrot_STRING, Parrot_PMC

leo