Doha GC isn't going to win any GCA fave awards, but it's been hosting the European Tour's Qatar Masters for some years now, and from a practical point of view could accommodate the Olympics. Personally, though, I cannot see Qatar winning the Games. Without trying to be too cynical it has to be a lot harder for an outlier candidate to win votes from the hundred-plus IOC committee than it is from the 24 members of FIFA's electorate. Plus the IOC was pretty thoroughly purged and reformed after the stink over the Salt Lake City bribery issues, and it has much stronger athlete representation - not the sort of people who are going to vote for hosting the Games in 50C heat.
Baku is an even longer shot, but I have picked up a number of potential golf projects there in the last year or so - in the unlikely event of them winning.
Istanbul has three courses - Istanbul GC, a nine hole course dating from 1895, plus two recent-ish developments, Klassis and Kemer. Neither, as far as I'm aware, is Olympic-worthy.
There's plenty of golf in Madrid, but I think, given the RFEG wanted to build a new course for the Ryder Cup, if the city won the Games they'd probably build new.
And Tokyo, given the shortage of building land in the region of the city, would I guess use an existing course - but no idea which one.