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

[Gregory Heytings]

> > I think this should preferably be automated.  The current ldefs-boot.el 
> > file in the trunk is 25 days old, running admin/update_autogen -L adds 
> > 247 lines and modifies 100 lines.
>
> It gets automaticallly updated on the first of the month.  It could be 
> more frequent, but it would seem like churn for no real reason most of 
> the time.

IMO once a week would be better.  An outdated ldefs-boot creates 
unnecessary warnings during the build.

> (It wouldn't make any difference to the issue that prompted this 
> report.)

That depends on the chosen solution.  You suggested copying ldefs-boot.el 
onto loaddefs.el when it is more recent.  I'm not entirely sure, but it 
seems to me that forcing a regeneration of the loaddefs files during make 
whenever ldefs-boot.el is more recent than loaddefs.el would be a better 
solution.