cosmetic: gen_makefile: place vim indenting rule comment
diff --git a/gen_makefile.py b/gen_makefile.py
index 05af4c8..5af7803 100755
--- a/gen_makefile.py
+++ b/gen_makefile.py
@@ -230,3 +230,5 @@
   for proj, deps in projects_deps:
     out.write(gen_make(proj, deps, configure_opts.get(proj), args.jobs,
                        make_dir, args.src_dir, build_dir, args.url))
+
+# vim: expandtab tabstop=2 shiftwidth=2