Fix imlicit declaration build warning

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/private.h

@@ -45,8 +45,10 @@ void      service_notify_cb(uev_t *w, void *arg, int events);
 
 const char *plugin_hook_str(hook_point_t no);
 int       plugin_exists    (hook_point_t no);
+
 void      plugin_run_hook  (hook_point_t no, void *arg);
 void      plugin_run_hooks (hook_point_t no);
+void      plugin_script_run(hook_point_t no);
 
 int       plugin_init      (uev_ctx_t *ctx);
 void      plugin_exit      (void);