merge(third_party/cgit): Import at master of 2020-01-11

Imported commit '723dc8fbcb' as
'third_party/cgit'.

third_party/cgit/gen-version.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+# Get version-info specified in Makefile
+V=$1
+
+# Use `git describe` to get current version if we're inside a git repo
+if test "$(git rev-parse --git-dir 2>/dev/null)" = '.git'
+then
+	V=$(git describe --abbrev=4 HEAD 2>/dev/null)
+fi
+
+new="CGIT_VERSION = $V"
+old=$(cat VERSION 2>/dev/null)
+
+# Exit if VERSION is uptodate
+test "$old" = "$new" && exit 0
+
+# Update VERSION with new version-info
+echo "$new" > VERSION
+cat VERSION