[tex-live] please improve logging messages

[Karl Berry]

              regen

Well, obviously that is quite terse :), but I don't think it is
"completely" meaningless.  It tells you the file was regenerated via a
script, not edited by hand.

Anyway, it was actually only yesterday that I figured out how to
automatically submit the changes to p4, and there was still a bug in it
today, (which is why I hadn't announced anything yet), so I was typing
the "regen" by hand.  In my automated version (Master/Tools/tlrebuild),
the submit message will be a little more verbose:
  regenerated by $0
I don't see any point to making it a complete English sentence.

    add the affected file name to the entry?

I submit everything at once, could be hundreds of files.  The list of
affected files is, of course, already being given to p4 in the
changelist.  It seems silly to repeat the information in the log message
when it's already there.