pass ext pointer in ext callback

Signed-off-by: Andy Green <andy@warmcat.com>
diff --git a/lib/private-libwebsockets.h b/lib/private-libwebsockets.h
index 2a11c11..edaeaa9 100644
--- a/lib/private-libwebsockets.h
+++ b/lib/private-libwebsockets.h
@@ -228,7 +228,7 @@
 
 struct libwebsocket {
 	const struct libwebsocket_protocols *protocol;
-	const struct libwebsocket_extension *
+	struct libwebsocket_extension *
 				   active_extensions[LWS_MAX_EXTENSIONS_ACTIVE];
 	void * active_extensions_user[LWS_MAX_EXTENSIONS_ACTIVE];
 	int count_active_extensions;