Fixed threading issues brought up by #74577. Make g_log_find_domain,

Fixed threading issues brought up by #74577. Make g_log_find_domain,

2002-03-14  Sebastian Wilhelmi  <wilhelmi@ira.uka.de>

	* glib/gmessages.c: Fixed threading issues brought up by
	#74577. Make g_log_find_domain, g_log_domain_new,
	g_log_domain_check_free and g_log_domain_get_handler require being
	called with g_messages_lock held and remove all internal locking
	in them. Then added proper locking to g_log_set_handler,
	g_log_remove_handler and g_logv. Problem spotted by Miroslaw
	Dobrzanski-Neumann <mne@mosaic-ag.com>. (#74577)