Subject: bug#48117: 28.0.50; Update of loaddefs.el during normal build is unreliable

From: Glenn Morris <[email-masked]>
Date: Fri, 30 Apr 2021 13:25:36 -0400

Another idea, FWIW:
In the make rule for $(lisp)/loaddefs.el, if loaddefs.el exists and is
older than ldefs-boot.el, start by copying the latter to the former.
This ought to limit how outdated loaddefs can get?