[2437] Add missing EXTRA_DIST

src/lib/dns/python/Makefile.am

@@ -47,6 +47,7 @@ EXTRA_DIST = tsigerror_python_inc.cc
 EXTRA_DIST += message_python_inc.cc
 EXTRA_DIST += nsec3hash_python_inc.cc
 EXTRA_DIST += rrset_collection_python_inc.cc
+EXTRA_DIST += zone_checker_python_inc.cc
 
 # Python prefers .so, while some OSes (specifically MacOS) use a different
 # suffix for dynamic objects.  -module is necessary to work this around.