NDOF: enable 3D mouse support on Mac by default

We used to require the 3Dconnexion driver installed at build-time so
this was turned off.

I reworked the code last year to remove the driver dependency so
there’s no reason not to enable this.

CMakeLists.txt

@@ -184,7 +184,6 @@ if (UNIX AND NOT APPLE)
 elseif(WIN32)
 	set(_init_JACK                           OFF)
 elseif(APPLE)
-	set(_init_INPUT_NDOF                     OFF)
 	set(_init_JACK                           OFF)
 	set(_init_OPENSUBDIV                     OFF)
 endif()