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

[Eli Zaretskii]

> From: Andrea Corallo <akrl@sdf.org>
> Cc: larsi@gnus.org, monnier@iro.umontreal.ca, 43725@debbugs.gnu.org
> Date: Tue, 09 Mar 2021 20:09:03 +0000
> 
> >> > Looking at a running Emacs, I see that it loads the *.eln files that
> >> > are preloaded.  I would expect those to be dumped into the emacs.pdmp
> >> > file, as it happens with *.elc files.  If all the stuff is dumped into
> >> > emacs.pdmp and loaded from there, why does Emacs still need to load
> >> > those *.eln files as shared libraries?
> >> 
> >> For loaded you mean entering in 'load_comp_unit'?
> >
> > I looked at the shared libraries loaded by the program as shown by the
> > GDB "info sharedlibrary" command.
> 
> Okay, that's normal.  The pdumper is dumping only the pseudovector
> representing the CU.  When the image is loaded pdumper calls
> 'load_comp_unit' to have the dynamic linker map again the .eln into
> memory.

This means that, unlike with preloaded *.elc files, one cannot delete
the preloaded *.eln files once the pdumper file is created, because
the *.eln files are still needed each time Emacs starts.