toolchain: drop old Makefile and init.sh script along with git hooks and slim down Python requirements.txt to just what we need

misc/git-hooks/post-merge.sh

@@ -1,2 +1,6 @@
-#!/bin/bash -e
-bash init.sh
+#!/bin/sh
+# Uninstall git hook used by old toolchain
+case "$0" in
+  */.git/hooks/*) rm "$0";;
+  *) echo "Inter git hooks are no longer used"
+esac