Readds icon_states removed by RKF in #4775

I'm not sure if this was done out of spite, as RKF said "those posters look awful" in IRC when they were merged before his and he had to merge his branch with dev or if this was an honest mistake overlooked by both RKF and the merger, but the defines are still there, the only thing missing is the actual sprites, which come up as blank when using posters 30-37.