devel/cgit: update 1.1 -> 1.2

• among other things, update to git 2.18

PR: 229841
Submitted by: Yasuhiro KIMURA <yasu@utahime.org>
Approved by: Marko Turk <mt@markoturk.info> (maintainer)
Relnotes: https://lists.zx2c4.com/pipermail/cgit/2018-July/004160.html