bug#48021: comp.el cannot be loaded without native compilation

[Glenn Morris <rgm@gnu.org>]

Andrea Corallo wrote:

>> ./src/emacs -Q -l ./lisp/emacs-lisp/comp.el
>>
>>    memq: Symbol's value as variable is void: comp-ctxt

> with a390a4965f comp-cstr-tests run clean for me also on vanilla build,
> please let me know if this is sufficient for the case you are testing.

Thanks. comp-cstr-test-70 is still failing for me.

The issue about comp.el being unloadable in builds without native
compilation remains (and hence test-custom-deps still fails).

I believe that in general, .el files should always be loadable, they
should just do nothing if not applicable.

For example, C-h f completion can try to load comp.el.