The XCode project is unmaintained. Speex has been replaced with Opus (which is in the repo). Ogg Vorbis was added to repo. SDL 1.2 replaced with SDL 2. ioquake3 now gets OpenGL functions at run-time instead of linking to OpenGL at compile time. I’m not sure why that would cause glXXX errors though.
The maintained build system uses
make from the command line as described at building ioquake3 on Mac.