res_pjsip: Print a helpful error message if sorcery registration fails

........

Merged revisions 402570 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@402572 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_pjsip/config_system.c

@@ -121,6 +121,7 @@ int ast_sip_initialize_system(void)
 	ast_sorcery_apply_default(system_sorcery, "system", "config", "pjsip.conf,criteria=type=system");
 
 	if (ast_sorcery_object_register(system_sorcery, "system", system_alloc, NULL, system_apply)) {
+		ast_log(LOG_ERROR, "Failed to register with sorcery (is res_sorcery_config loaded?)\n");
 		ast_sorcery_unref(system_sorcery);
 		system_sorcery = NULL;
 		return -1;