[PATCH] emacs: use (system-name) instead of system-name

[David Bremner]

Jani Nikula <jani at nikula.org> writes:

> Fix the deprecation warning:
>
> In notmuch-maildir-fcc-make-uniq-maildir-id:
> emacs/notmuch-maildir-fcc.el:279:53:Warning: ‘system-name’ is an obsolete
>     variable (as of 25.1); use (system-name) instead

pushed to master

d