ports/66762: Update port: games/xpilot-ng (split into games/xpilot-ng-server and games/xpilot-ng-client)

[Jean-Yves Lefort]

Better would be to modify bsd.port.mk so that USE_GCC accepts a range
of versions (like USE_PYTHON does). But for now setting USE_GCC=3.3
will not hurt.