We won't support a.out on arm64/aarch64. As such there will be no need to

support it in nlist(3).

Reviewed by:	emaste
Sponsored by:	The FreeBSD Foundation

lib/libc/gen/nlist.c

@@ -47,7 +47,10 @@ __FBSDID("$FreeBSD$");
 #include <unistd.h>
 #include "un-namespace.h"
 
+/* There is no a.out support on arm64 */
+#ifndef __aarch64__
 #define _NLIST_DO_AOUT
+#endif
 #define _NLIST_DO_ELF
 
 #ifdef _NLIST_DO_ELF