Linux: Handle export preset forward compat with 4.3+ platform name

(cherry picked from commit d534c67d91b0e4c439bace65a1b51c22a194d07f)

editor/export/editor_export.cpp

@@ -227,6 +227,10 @@ void EditorExport::load_config() {
 		}
 
 		String platform = config->get_value(section, "platform");
+		// Forward compatibility with Linux platform after 4.3.
+		if (platform == "Linux") {
+			platform = "Linux/X11";
+		}
 
 		Ref<EditorExportPreset> preset;