Mark BROKEN: fails to link

c++ -O2 -pipe -DIMAGE_PATH=\"/usr/local/lib/X11/glclock/\" -fstack-protector -fno-strict-aliasing -L/usr/local/lib -o glclock main.o glclock.o GLObject.o GLextensions.o PnmIO.o MString.o -lglut -lGLU -lGL -lXi -lXmu -lXext -lX11 -lm
GLextensions.o: In function `IsSupported_EXT_polygon_offset()':
GLextensions.cpp:(.text+0x1027): undefined reference to `glPolygonOffsetEXT'

Reported by: pkg-fallout