termbox: use gerrit repo instead of phab mirror

The phabricator mirror is likely the legacy of termbox being mirrored
from github. Setting it directly to gerrit avoids delays between the
source and the mirror when updating the submodule version in Wikibase.

Change-Id: I4fd68f0c2d73e7763f9c480287e6ddfc223245a8

Author: jakobw

.gitmodules

@@ -12,7 +12,7 @@
 	url = https://phabricator.wikimedia.org/source/wikibase-data-model.git
 [submodule "view/lib/wikibase-termbox"]
 	path = view/lib/wikibase-termbox
-	url = https://phabricator.wikimedia.org/source/wikibase-termbox
+	url = https://gerrit.wikimedia.org/r/wikibase/termbox
 
 [submodule "lib/resources/wikibase-api"]
 	path = lib/resources/wikibase-api