Thread openrecoveryscript action to properly display action page

The action page fails to display properly during ORS processing
unless we thread the ORS action. Based upon the work done in this
patch set by _that:
https://gerrit.omnirom.org/#/c/11226

Change-Id: I6dac790ac26d9b3a02df778516fea011d67aea70
diff --git a/gui/objects.hpp b/gui/objects.hpp
index bf07c86..124c926 100644
--- a/gui/objects.hpp
+++ b/gui/objects.hpp
@@ -288,6 +288,7 @@
 	void operation_end(const int operation_status);
 	static void* command_thread(void *cookie);
 	static void* sideload_thread_fn(void *cookie);
+	static void* openrecoveryscript_thread_fn(void *cookie);
 	time_t Start;
 
 	// map action name to function pointer