Comment in verilog-mode.el about supported versions

[Tino Calancha]

Hi,

in the comentary of
lisp/progmodes/verilog-mode.el
you can find following comment:
;;    This code supports Emacs 21.1 and later
;;    And XEmacs 21.1 and later
;;    Please do not make changes that break Emacs 21.  Thanks!

I could understand this comment in a version of this file
elsewhere, e.g. ELPA, but not in the built-in version in Emacs.
Why is this comment needed?
Is it OK to drop from the master branch this kind of comments?

Thanks,
Tino