Avoid asserting in zero-arg Do_Routine() case
Avoid asserting in zero-arg Do_Routine() case

The new assert protecting the access of arguments at indices bigger
than the number of arguments was tripping when a routine with no
arguments was invoked.  (Found by running gtk.r sample.)

kealist/ren-c,kealist/ren-c,hostilefork/rebol,draegtun/ren-c,giuliolunati/ren-c,codebybrett/ren-c,kealist/ren-c,draegtun/ren-c,hostilefork/rebol,giuliolunati/ren-c,codebybrett/ren-c,kealist/ren-c,giuliolunati/ren-c,kealist/ren-c,giuliolunati/ren-c,rgchris/ren-c,draegtun/ren-c,codebybrett/ren-c,codebybrett/ren-c,codebybrett/ren-c,rgchris/ren-c,kealist/ren-c,hostilefork/rebol,hostilefork/rebol,codebybrett/ren-c,rgchris/ren-c,hostilefork/rebol,draegtun/ren-c,draegtun/ren-c,rgchris/ren-c,giuliolunati/ren-c,hostilefork/rebol,rgchris/ren-c,draegtun/ren-c