Fix input handling of RUN method on Allegro CL

On Allegro CL the RUN method does not obtain input from a stream
correctly. Just creating an echo stream does not work, one needs to
copy the data to the provided stream in the :input form of
excl.osi:with-command-io.

Fixes sellout/external-program#17

Signed-off-by: Utz-Uwe Haus <lisp@uuhaus.de>