We added a `.dir-locals.el` in commit: 9a77017d87
There's no need to have it per-file, with that people might think
to add other editors, which is the wrong direction.
Closes: #1206
Approved by: jlebon
This is inspired by the [Coccinelle](http://coccinelle.lip6.fr/) usage
in systemd. I also took it a bit further and added infrastructure
to have spatches which should never apply. This acts as a blacklist.
The reason to do the latter is that coccinelle is *way* more powerful than the
regular expresssions we have in `make syntax-check`.
I started with blacklisting `g_error_free()` directly. The reason that's bad is
it leaves a dangling pointer.
Closes: #754
Approved by: jlebon