Remove LocaleGuard from Session::immediately_post_engine method

I think this was only to protect the float <=> string conversion in
Session::setup_click_state related to click gain which is now using
PBD::to_string/string_to and so no longer necessary.

libs/ardour/session.cc

@@ -583,7 +583,6 @@ Session::immediately_post_engine ()
 	}
 
 	try {
-		LocaleGuard lg;
 		BootMessage (_("Set up LTC"));
 		setup_ltc ();
 		BootMessage (_("Set up Click"));