[XR] Fix building on MinGW

Destructor was defined in multiple places due to multiple inheritance

modules/openxr/extensions/openxr_extension_wrapper_extension.cpp

@@ -238,3 +238,6 @@ OpenXRExtensionWrapperExtension::OpenXRExtensionWrapperExtension() :
 		Object(), OpenXRExtensionWrapper() {
 	openxr_api.instantiate();
 }
+
+OpenXRExtensionWrapperExtension::~OpenXRExtensionWrapperExtension() {
+}