This fixes buildworld when src/games doesn't exist (this may not be
"officially" supported, but there's no sense in making it harder for
somebody that wants to do it).
PR: 29162
Submitted by: Stewart Morgan <stewart@nameless-uk.com>
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.