Show current display server in Editor window tooltip

(cherry picked from commit 62968dd437)

Source/Engine/Platform/Base/PlatformBase.h

@@ -369,6 +369,11 @@ public:
     /// </summary>
     API_PROPERTY() static PlatformType GetPlatformType();
 
+    /// <summary>
+    /// Returns the display server name on Linux.
+    /// </summary>
+    API_PROPERTY() static String GetDisplayServer() = delete;
+
     /// <summary>
     /// Returns true if is running 64 bit application (otherwise 32 bit). It's compile-time constant.
     /// </summary>