[Bug ada/64492] Disabling libada prevents building gnattools-cross

[simon at pushface dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64492

--- Comment #12 from simon at pushface dot org ---
(In reply to Eric Botcazou from comment #10)
> This should work with Arno's incantation now.

Confirmed. Thanks.

I have to say, though, that configuring with --disable-libada
--enable-cross-gnattools means you can just “make; make install” without any
need for incantations!