Fix MSVC builds (binding external static members)

This Revert "Lua GUI Instance update: prepare for template scripts"
commit c37cdf548d.

gtk2_ardour/ardour_ui.cc

@@ -3935,7 +3935,6 @@ ARDOUR_UI::meta_session_setup (const std::string& script_path)
 	}
 
 	LuaState lua;
-	lua.Print.connect (&LuaInstance::_lua_print);
 	lua.sandbox (true);
 
 	lua_State* L = lua.getState();

gtk2_ardour/luainstance.cc

@@ -974,9 +974,7 @@ using namespace ARDOUR_UI_UTILS;
 using namespace PBD;
 using namespace std;
 
-void
-LuaInstance::_lua_print (std::string s)
-{
+static void _lua_print (std::string s) {
 #ifndef NDEBUG
 	std::cout << "LuaInstance: " << s << "\n";
 #endif
@@ -1750,7 +1748,7 @@ LuaCallback::get_state (void)
 void
 LuaCallback::init (void)
 {
-	lua.Print.connect (&LuaInstance::_lua_print);
+	lua.Print.connect (&_lua_print);
 	lua.sandbox (false);
 
 	lua.do_command (

gtk2_ardour/luainstance.h

@@ -91,8 +91,6 @@ public:
 
 	static void render_action_icon (cairo_t* cr, int w, int h, uint32_t c, void* i);
 
-	static void _lua_print (std::string s);
-
 	void set_session (ARDOUR::Session* s);
 
 	int set_state (const XMLNode&);