config: register the devel.check-locks config

mercurial/configitems.py

@@ -62,6 +62,9 b" coreconfigitem('devel', 'all-warnings',"
 coreconfigitem('devel', 'bundle2.debug',
     default=False,
 )
+coreconfigitem('devel', 'check-locks',
+    default=False,
+)
 coreconfigitem('patch', 'fuzz',
     default=2,
 )