bug#58509: 29.0.50; Synchronous nativecomp

[Eli Zaretskii]

> From: Andrea Corallo <akrl@sdf.org>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>, 58509@debbugs.gnu.org
> Date: Tue, 18 Oct 2022 13:55:18 +0000
> 
> The attached works for me for fixing the trampoline issue (unless I did
> something wrong reproducing).
> 
> I named the flag -no-comp-spawn from the variable it controls.  Happy to
> rename it if we have something better, but being for internal use only
> maybe is already okay?

On second thought: why do we need a special knob for that?  Could we
instead _always_ compile trampolines "without spawning" in a --batch
session?  IOW, when do we need --batch to compile trampolines
asynchronously?