Start up crash of LLErrorThread due to corrupt map in CheckLevelMap

Wrapped gSettings and the global objects returned by Settings::get() and
Globals::get() in AIThreadSafe, forcing thread-safe access.

This solves the problem of possible corruption of the various LevelMap's
in LLError::Settings due to thread unsafe accesses.

indra/newview/llstartup.cpp

@@ -985,7 +985,7 @@ bool idle_startup()
 			);
 
 		// Overwrite default user settings with user settings								 
-		LLAppViewer::instance()->loadSettingsFromDirectory("Account");
+		LLAppViewer::instance()->loadSettingsFromDirectory(AIReadAccess<settings_map_type>(gSettings), "Account");
 
 		// Need to set the LastLogoff time here if we don't have one.  LastLogoff is used for "Recent Items" calculation
 		// and startup time is close enough if we don't have a real value.