provide libGL.so and is therefore useful for nvidia users (since
x11/nvidia-driver already provides libGL.so). That is, to express a
dependency on libGLU, do this:
.if defined(WITH_NVIDIA_GL)
RUN_DEPENDS+= ${LINUXBASE}/usr/X11R6/lib/libGLU.so.1:${PORTSDIR}/graphics/linux-libGLU
.else
RUN_DEPENDS+= ${LINUXBASE}/usr/X11R6/lib/libGLU.so.1:${PORTSDIR}/graphics/linux_dri
.endif