Fix display of correct program name

src/anetz/main.c

@@ -118,7 +118,7 @@ int main(int argc, char *argv[])
 
 	if (!kanal) {
 		printf("No channel (\"Kanal\") is specified, I suggest channel 30.\n\n");
-		print_help(argv[0]);
+		print_help(argv[-skip_args]);
 		return 0;
 	}
 

src/bnetz/main.c

@@ -130,7 +130,7 @@ int main(int argc, char *argv[])
 
 	if (!kanal) {
 		printf("No channel (\"Kanal\") is specified, I suggest channel 1.\n\n");
-		print_help(argv[0]);
+		print_help(argv[-skip_args]);
 		return 0;
 	}
 

src/cnetz/main.c

@@ -172,7 +172,7 @@ int main(int argc, char *argv[])
 	}
 
 	if (mandatory) {
-		print_help(argv[0]);
+		print_help(argv[-skip_args]);
 		return 0;
 	}
 

src/nmt/main.c

@@ -215,7 +215,7 @@ int main(int argc, char *argv[])
 	}
 
 	if (mandatory) {
-		print_help(argv[0]);
+		print_help(argv[-skip_args]);
 		return 0;
 	}