wplua: move under modules/module-lua-scripting

It's unlikely that wplua will ever be useful outside the context
of module-lua-scripting, so let's move it to keep all the code in one place

modules/module-lua-scripting/wplua/private.h

@@ -0,0 +1,37 @@
+/* WirePlumber
+ *
+ * Copyright © 2020 Collabora Ltd.
+ *    @author George Kiagiadakis <george.kiagiadakis@collabora.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#ifndef __WPLUA_PRIVATE_H__
+#define __WPLUA_PRIVATE_H__
+
+#include "wplua.h"
+
+G_BEGIN_DECLS
+
+/* boxed.c */
+void _wplua_init_gboxed (lua_State *L);
+
+/* closure.c */
+void _wplua_init_closure (lua_State *L);
+
+/* object.c */
+void _wplua_init_gobject (lua_State *L);
+
+/* userdata.c */
+GValue * _wplua_pushgvalue_userdata (lua_State * L, GType type);
+gboolean _wplua_isgvalue_userdata (lua_State *L, int idx, GType type);
+
+int _wplua_gvalue_userdata___gc (lua_State *L);
+int _wplua_gvalue_userdata___eq (lua_State *L);
+
+/* wplua.c */
+int _wplua_pcall (lua_State *L, int nargs, int nret);
+
+G_END_DECLS
+
+#endif