master c430f7e breaks diff-mode fontification

[Stephen Berman <stephen.berman@gmx.net>]

This change breaks diff-mode fontification:

> branch: master
> commit c430f7e23fc2c22f251ace4254e37dea1452dfc3
> Author: Mark Oteiza <mvoteiza@udel.edu>
> Commit: Mark Oteiza <mvoteiza@udel.edu>
>
>     Remove some face aliases obsoleted in 22.1

To reproduce (after git pull and make bootstrap):

0. emacs -Q
1. C-x v L RET <path to emacs master git root> RET
2. In the *vc-change-log* buffer type `d' on one of the entries.
=> The diff displayed in the *vc-diff* buffer lack the expected faces on
   the removed and added lines, and the *Messages* buffer contains these
   messages:
Error during redisplay: (jit-lock-function 1) signaled (void-variable diff-hunk-header)
Error during redisplay: (jit-lock-function 501) signaled (void-variable diff-removed)
Error during redisplay: (jit-lock-function 1001) signaled (void-variable diff-hunk-header)
Error during redisplay: (jit-lock-function 1501) signaled (void-variable diff-context)

If prior to step 1 above I evaluate the file diff-mode.el from emacs-25
(i.e. the version before the above commit), then after 2 the *vc-diff*
buffer is fontified as expected and there no such error messages in *Messages*.

Steve Berman