#2 Allow invocation in the same step where one defines the exte

[Rony G. Flatscher]

It seems that at the moment one needs to first define
the signature of a desired function via a stem, and
register it as an external Rexx function. In the next
step one uses the same stem (containing the arguments
supplied by Rexx) as an argument to that external
function each time one invokes it.

Many times it would be sufficient, if one is able to
define the interface and to supply the needed arguments
with the same invocation to GCI.

So the suggestion: allow for defining *and* invoking an
external function in one step. (Do not impose the need
to first register that function as an external Rexx
function.)

---rony