[Openal] OpenAL Soft's alcOpenDevice returns null

[Stephen A]

Ok, for people who encounter the same issues, it's as Chris said from the  
start: the dsound part wasn't getting built.

I reinstalled the DX SDK and the problem went away. There was no  
indication that there was something amiss (CMake reported dsound support  
would be built).

Hope this helps someone in the future, and sorry for the false alarm. :)