Fix iOS Build (#29)

Fixes #28

Author: bobbyg603

Runtime/BugSplat.cs

@@ -6,10 +6,13 @@
 using System.Net.Http;
 using System.IO;
 using System.Runtime.InteropServices;
-using UnityEngine.Windows;
 using System.Linq;
 using BugSplatDotNetStandard;
 
+#if UNITY_STANDALONE_WIN
+using UnityEngine.Windows;
+#endif
+
 namespace BugSplatUnity
 {
     /// <summary>