Fix Segfault In features-config.c When Application Has No Arguments

Some applications do not require arguments.  Therefore, when parsing application
maps in features.conf, it is possible that app_data will be set to NULL.

* This patch sets app_data to "" if it is NULL.

Review: https://reviewboard.asterisk.org/r/2804
........

Merged revisions 399294 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@399295 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/features_config.c

@@ -1348,6 +1348,11 @@ static int applicationmap_handler(const struct aco_option *opt,
 		*slash = '\0';
 	}
 
+	/* Some applications do not require arguments. */
+	if (!args.app_data) {
+		args.app_data = "";
+	}
+
 	/* Two syntaxes allowed for applicationmap:
 	 * Old: foo = *1,self,NoOp,Boo!,default
 	 * New: foo = *1,self,NoOp(Boo!),default