One of my several reasons of opposition to golf in the Olympics is that it puts additional requirements on countries that may just not have any facilities capable of hosting a world class event. Angel Cabrera was apparently interviewed about it and he thinks they may have to build one. I don't know anything about the courses Wayne mentioned; perhaps Angel doesn't either. Or maybe those courses just aren't suitable?
I suppose they could build one if necessary, but that seems like a rapid time frame to select a site, find an architect, design the course, build the course, and have the course actually grow in enough to host an event featuring the world's best. And afterwards, will Rio/Brazil have any use for the course? I'm not counting on the Olympics to create a golf boom in Brazil, although maybe there will be enough people interested in playing there.