bug#28403: 25.2; find-tag works, but xref-find-definitions

[Eli Zaretskii]

> Cc: wbe@psr.com, 28403@debbugs.gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Tue, 19 Sep 2017 03:44:28 +0300
> 
> On 9/14/17 8:13 PM, Eli Zaretskii wrote:
> 
> > I just feel that having a user-friendly defcustom would be more
> > future-proof.  Like I said: it's a fire escape.  Every complex feature
> > needs one.
> 
> My point is if we document it enough for the majority of the users to 
> find it, it would also make it more likely that they go the fire escape 
> route instead of using etags in the right way. And then get some other 
> wrong impression about xref-find-definitions.

Fire escapes don't have to be documented, just pointed out when and if
someone really needs them.