Cut down comment volume in %c-eval.c
Cut down comment volume in %c-eval.c

There was too much comment whitespace in %c-eval.c considering how long
a function Eval_Core_Throws() is.  This cuts it down to be more
manageable, and also reduces the `label:;` to just the cases that need
it, but comments the cases that need it.

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