bug#43725: 28.0.50; Include feature/native-comp into master

[Eli Zaretskii]

> From: Andrea Corallo <akrl@sdf.org>
> Cc: 43725@debbugs.gnu.org
> Date: Fri, 02 Oct 2020 19:58:32 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Date: Fri, 02 Oct 2020 19:39:29 +0000
> >> From: Andrea Corallo via "Bug reports for GNU Emacs,
> >>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> >> 
> >> redefining primitives does not take effect in optimized code
> >
> > Why doesn't it?  Can it be made to take effect, like it does in
> > interpreted code?
> 
> Mmmh, I think technically we could, similarly to what we do for the
> advice, synthesize compile and install a trampoline.  This would read
> the symbol-function and calls what's in inside.
> 
> This trampoline installation would be triggered inside Ffset.
> 
> So yeah I think we could, if that's the preferred way I can try this
> way.

Lars, Stefan: do you agree that this is the preferred way?