librefetch.conf: only select a graphical DIFFPROG if DISPLAY is set.

There was a request on the bug tracker a while ago to not include
graphical programs in the list searched, as sometimes they used
libretools without X.  We closed it as WONTFIX because it's a
configuration option; if you don't like the default value, then set it
to something different.

But, checking for DISPLAY is trivial, and probably makes more people
happy out-of-the-box, which is good.  I don't know why I didn't think
of it then.

0 files changed, 0 insertions, 0 deletions