CA-164176: Make sure that the Install Update does not get stuck on precheck stage after cleanup on slave

- implement GetHashCode on HostOutOfSpaceProblem

Signed-off-by: Mihaela Stoica <mihaela.stoica@citrix.com>

XenAdmin/Diagnostics/Problems/HostProblem/HostOutOfSpaceProblem.cs

@@ -123,5 +123,10 @@ namespace XenAdmin.Diagnostics.Problems.HostProblem
                 return false;
             return diskSpaceReq.Equals(other.diskSpaceReq);
         }
+
+        public override int GetHashCode()
+        {
+            return diskSpaceReq != null ? diskSpaceReq.GetHashCode() : 0;
+        }
     }
 }