support building external buildings from workers with infinite range (like walls and roads built from the town hall in warcraft1)

src/ai/ai_building.cpp

@@ -181,7 +181,8 @@ VisitResult BuildingPlaceFinder::Visit(TerrainTraversal &terrainTraversal, const
 			*resultPos = pos;
 		}
 	}
-	if (CanMoveToMask(pos, movemask)) { // reachable
+	if (CanMoveToMask(pos, movemask)
+		|| (worker.Type->RepairRange == InfiniteRepairRange && type.BuilderOutside)) { // reachable, or unit can build from outside and anywhere
 		return VisitResult_Ok;
 	} else { // unreachable
 		return VisitResult_DeadEnd;

src/include/unittype.h

@@ -525,6 +525,7 @@ public:
 	int BurnPercent;                /// Burning percent.
 	int BurnDamageRate;             /// HP burn rate per sec
 	int RepairRange;                /// Units repair range.
+#define InfiniteRepairRange INT_MAX
 	char *CanCastSpell;             /// Unit is able to use spells.
 	char *AutoCastActive;           /// Default value for autocast.
 	int AutoBuildRate;              /// The rate at which the building builds itself

src/tolua/stratagus.pkg

@@ -55,6 +55,7 @@ $]
 #define MaxResourceInfo MaxCosts + 4
 #define PlayerMax 16
 #define PlayerNumNeutral (PlayerMax - 1)
+#define InfiniteRepairRange 0x7FFFFFFF
 
 #define NoButton 0
 #define LeftButton 2