editors/emacs-devel: Update to latest master branch commit, 4f2b415
This update includes an Emacs major version change from 27.0.50 to 28.0.50.
Ports that may depend on editors/emacs-devel must chase this update
with a PORTREVISION bump.
Submitted by: ashish (maintainer)
Differential Revision: https://reviews.freebsd.org/D23012