instrument FindUnitsInCircle for perf

OpenRA.Game/WorldUtils.cs

@@ -25,6 +25,7 @@ using System.Linq;
 using OpenRA.FileFormats;
 using OpenRA.GameRules;
 using OpenRA.Traits;
+using OpenRA.Support;
 
 namespace OpenRA
 {
@@ -92,6 +93,8 @@ namespace OpenRA
 		}
 
 		public static IEnumerable<Actor> FindUnitsInCircle(this World world, float2 a, float r)
+		{
+			using (new PerfSample("FindUnitsInCircle"))
 			{
 				var min = a - new float2(r, r);
 				var max = a + new float2(r, r);
@@ -104,6 +107,7 @@ namespace OpenRA
 
 				return inBox.Where(x => (x.CenterLocation - a).LengthSquared < r * r);
 			}
+		}
 
 		public static IEnumerable<int2> FindTilesInCircle(this World world, int2 a, int r)
 		{