bug#26181: Remove etags

[Dmitry Gutov <dgutov@yandex.ru>]

On 20.03.2017 01:15, Glenn Morris wrote:

> I've never understood why Emacs includes a tags program.
> It's not part of the normal remit of a text editor.

FWIW, it has been handy when we introduced xref and started treating the 
tags a bit more strictly.

> The situation has changed since then in that etags no longer has a
> maintainer (IIUC).

AFAIK Eli is the maintainer now. And it's handy to have for now, at 
least until Universal Ctags is widely available across distributions, 
handles all languages as well as etags does, and outputs correct entries 
WRT implicit/explicit tag names (not 100% sure there is a problem, but 
it's something that we had to fix in etags recently, at least).

Having all these conditions satisfied seems to be a .

> Having our own tags program means we can tweak it to work better for our
> own code; but conversely it would be better if our code Just Worked with
> standard (ie external) tools.

The latter might mean learning to use the ctags output (Vim format).