fill_config.py: ignore templates starting with 'common_'

It's useful to include common parts in numerous cfg files, using the
${include(path)} command. So far they were called common_* and stored outside
of the templates dir (e.g. for logging). So far all files in a templates dir
are seen as templates, so the common files had to be stored in a different dir,
which is a bit senseless.

Allow storing them in the same dir with the templates: ignore all files
starting with 'common_'.

Change-Id: I74446dc0a7f51d4f231e8758a691abb675e87483

net/fill_config.py

@@ -210,6 +210,10 @@ for tmpl_name in sorted(os.listdir(tmpl_dir)):
   if tmpl_name.startswith('.'):
     continue
 
+  # omit files to be included by other files
+  if tmpl_name.startswith('common_'):
+    continue
+
   tmpl_src = os.path.join(tmpl_dir, tmpl_name)
   dst = tmpl_name