bug#60525: 29.0.60; tree-sitter support in semantic-symref

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: dgutov@yandex.ru,  larsi@gnus.org,  juri@linkov.net,  
> 60525@debbugs.gnu.org
> Date: Wed, 04 Jan 2023 13:20:26 -0500
> 
> - move the info from `semantic-symref-filepattern-alist` to
>   a buffer-local `semantic-symref-filepattern` which is set by the major
>   modes, so the same setting can be shared by the various modes like all
>   the other buffer-local settings (`comment-start`, ...).
> 
> BTW, I see that the info provided by `semantic-symref-filepattern-alist`
> could be (re)used also in `C-u M-x grep`.

Fine with me, but that is hardly for the release branch.