Update pre-commit hook to find checkIncludes in its new location

Also add a temporary script to redirect the hook, if people don't
upgrade for a bit.

scripts/maint/checkIncludes.py

@@ -0,0 +1,14 @@
+#!/usr/bin/python
+# Copyright 2018 The Tor Project, Inc.  See LICENSE file for licensing info.
+
+# This file is no longer here; see practracker/includes.py for this
+# functionality.  This is a stub file that exists so that older git
+# hooks will know where to look.
+
+import sys, os
+
+dirname = os.path.split(sys.argv[0])[0]
+new_location = os.path.join(dirname, "practracker", "includes.py")
+python = sys.executable
+
+os.execl(python, python, new_location, *sys.argv[1:])