Make considerably more progress on AARCH64

- Utilities like pledge.com now build
- kprintf() will no longer balk at 48-bit addresses
- There's a new aarch64-dbg build mode that should work
- gc() and defer() are mostly pacified; avoid using them on aarch64
- THIRD_PART_STB now has Arm Neon intrinsics for fast image handling

libc/runtime/utmp.c

@@ -0,0 +1,72 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/runtime/utmp.h"
+#include "libc/errno.h"
+#include "libc/runtime/utmpx.h"
+
+void setutent(void) {
+}
+
+void endutent(void) {
+}
+
+void endutxent(void) {
+}
+
+struct utmp *getutent(void) {
+  return 0;
+}
+
+void updwtmp(const char *x, const struct utmp *y) {
+}
+
+void updwtmpx(const char *x, const struct utmpx *y) {
+}
+
+void setutxent(void) {
+}
+
+struct utmp *getutid(const struct utmp *x) {
+  return 0;
+}
+
+struct utmpx *getutxent(void) {
+  return 0;
+}
+
+struct utmpx *getutxid(const struct utmpx *x) {
+  return 0;
+}
+
+struct utmpx *getutxline(const struct utmpx *x) {
+  return 0;
+}
+
+int __utmpxname() {
+  errno = ENOTSUP;
+  return -1;
+}
+
+int utmpname(const char *x) {
+  return __utmpxname();
+}
+
+int utmpxname(const char *x) {
+  return __utmpxname();
+}