CANNOT_DUMP and portable dumper

[Glenn Morris]

CANNOT_DUMP used to mean "Emacs cannot be dumped on your system".
Now it means "Emacs should not support unexec".

This means that current master builds using portable dumper have
CANNOT_DUMP set in system-configuration-features.
I keep being confused by this (in bug reports).

Maybe it makes sense to re-use CANNOT_DUMP from an implementation point
of view, but perhaps it should at least not be listed in
system-configuration-features any more (replaced by eg PORTABLE_DUMP)?

(Or maybe it's just me being confused.)

PS Perhaps etc/DEBUG "Running Emacs built with malloc debugging
packages" is now outdated in this regard?