Instead of overloading the mongod process name can we just have the server test the name of the executable that spawned it and change behaviour. So basically create a symlink /usr/sbin/mongoc -> /usr/sbin/mongod and if argv[0] ends with mongoc enable --configsvr.

It's backward compatible, keeps things consistent (mongoc, mongod, mongos), makes it easy to tell at a glance what's running and has an ancillary benefit of shortening the argument list.