Enabling sound in xpilot-ng-server

[Clint Olsen]

Yet again, I'm having fun with these WITH_* options, and I can't seem to
coerce the configure phase to enable sound with this port.

My config after hacking the Makefile looks like:

# This file is auto-generated by 'make config'.
# No user-servicable parts inside!
# Options for xpilot-ng-client-4.7.2_1
_OPTIONS_READ=xpilot-ng-client-4.7.2_1
WITH_SDL=true
WITH_SOUND=true

However, when I examine config.log down in the work area, I see no
sound switches being thrown, and thus no sound.

Someone please throw me a cluepon here.

-Clint