Replaced a CONFIG_* name with a UML_CONFIG_* name.

arch/um/main.c

@@ -92,7 +92,7 @@ int main(int argc, char **argv, char **envp)
 		exit(1);
 	}
 
-#ifdef CONFIG_MODE_TT
+#ifdef UML_CONFIG_MODE_TT
 	/* Allocate memory for thread command lines */
 	if(argc < 2 || strlen(argv[1]) < THREAD_NAME_LEN - 1){