(svn r18726) -Fix [FS#3463]: with non-uniform industries the 'supplies' text when building a station could be incorrect (missing a cargo)

-Change [NoAI]: AITile::GetCargoProduction now returns the number of producers and not the number of tiles of producers.
-Fix [NoAI]: AITileList_IndustryProducing would omit some tiles for at which a station would get cargo.

src/tilearea_type.h

@@ -53,6 +53,13 @@ struct TileArea {
 		this->w    = 0;
 		this->h    = 0;
 	}
+
+	/**
+	 * Does this tile area intersect with another?
+	 * @param ta the other tile area to check against.
+	 * @return true if they intersect.
+	 */
+	bool Intersects(const TileArea &ta) const;
 };
 
 #endif /* TILEAREA_TYPE_H */