GRF: Add extra road/tram type flag: not available to AI/GS

src/table/newgrf_debug_data.h

@@ -861,6 +861,9 @@ class NIHRoadType : public NIHelper {
 					HasBit(rti->flags, ROTF_HIDDEN) ? 'h' : '-',
 					HasBit(rti->flags, ROTF_TOWN_BUILD) ? 'T' : '-');
 			print(buffer);
+			seprintf(buffer, lastof(buffer), "    Extra Flags: %c",
+					HasBit(rti->extra_flags, RXTF_NOT_AVAILABLE_AI_GS) ? 's' : '-');
+			print(buffer);
 			seprintf(buffer, lastof(buffer), "    Powered: 0x" OTTD_PRINTFHEX64, rti->powered_roadtypes);
 			print(buffer);
 		};

src/table/roadtypes.h

@@ -63,6 +63,9 @@ static const RoadTypeInfo _original_roadtypes[] = {
 		/* flags */
 		ROTFB_TOWN_BUILD,
 
+		/* extra flags */
+		RXTFB_NONE,
+
 		/* cost multiplier */
 		8,
 
@@ -143,6 +146,9 @@ static const RoadTypeInfo _original_roadtypes[] = {
 		/* flags */
 		ROTFB_CATENARY | ROTFB_NO_HOUSES,
 
+		/* extra flags */
+		RXTFB_NONE,
+
 		/* cost multiplier */
 		16,