remove define version and added custom define

Author: ritamerkl

Assets/Tests/InputSystem/CoreTests_MouseEvents.cs

@@ -1,4 +1,4 @@
-#if UNITY_6000_4_OR_NEWER
+#if UNITY_INPUTSYSTEM_HAS_MOUSE_SCRIPT_EVENTS_SUPPORTED
 using System;
 using System.Collections;
 using System.Collections.Generic;

Packages/com.unity.inputsystem/InputSystem/InputManager.cs

@@ -3705,7 +3705,7 @@ private unsafe void OnUpdate(InputUpdateType updateType, ref InputEventBuffer ev
             ////       same goes for events that someone may queue from a change monitor callback
             InvokeAfterUpdateCallback(updateType);
             //send pointer data to backend for OnMouseEvents
-#if UNITY_6000_4_OR_NEWER
+#if UNITY_INPUTSYSTEM_HAS_MOUSE_SCRIPT_EVENTS_SUPPORTED
             var pointer = Pointer.current;
             if (pointer != null && gameIsPlaying)
                 NativeInputSystem.DoSendMouseEvents(pointer.press.isPressed, pointer.press.wasPressedThisFrame, pointer.position.x.value, pointer.position.y.value);

Packages/com.unity.inputsystem/InputSystem/Unity.InputSystem.asmdef

@@ -116,7 +116,12 @@
             "name": "Unity",
             "expression": "6000.3.0a6",
             "define": "UNITY_INPUT_SYSTEM_PLATFORM_POLLING_FREQUENCY"
-        }
+        },
+	{
+	    "name": "Unity",
+            "expression": "6000.4.0a1",
+            "define": "UNITY_INPUTSYSTEM_HAS_MOUSE_SCRIPT_EVENTS_SUPPORTED"
+	}
     ],
     "noEngineReferences": false
 }