There's a problem compiling the latest GDI builds, last version is r6045, while the actual is r6051.
All it's showing right now is the compiler log. There are 4 errors in the log.
The next build should work, at least that is what wernieman said at the German forum.
Strictly speaking, there's been a problem compiling the nightlies for Windows in the last couple of months. Hopefully this will make it work for all again.
I take it then that the SDL nightly is being built without multithreading?