Fix bugs and make improvements

- Get clone() working on FreeBSD
- Increase some Python build quotas
- Add more atomic builtins to chibicc
- Fix ASAN poisoning of alloca() memory
- Make MODE= mandatory link path tinier
- Improve the examples folder a little bit
- Start working on some more resource limits
- Make the linenoise auto-complete UI as good as GNU readline
- Update compile.com, avoiding AVX codegen on non-AVX systems
- Make sure empty path to syscalls like opendir raises ENOENT
- Correctly polyfill ENOENT vs. ENOTDIR on the New Technology
- Port bestline's paredit features to //third_party/linenoise
- Remove workarounds for RHEL 5.0 bugs that were fixed in 5.1

test/libc/runtime/clone_test.c

@@ -1,50 +0,0 @@
-/*-*- 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 2021 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/assert.h"
-#include "libc/calls/calls.h"
-#include "libc/dce.h"
-#include "libc/log/backtrace.internal.h"
-#include "libc/mem/mem.h"
-#include "libc/runtime/gc.internal.h"
-#include "libc/runtime/symbols.internal.h"
-#include "libc/sysv/consts/clone.h"
-#include "libc/testlib/testlib.h"
-#include "libc/time/time.h"
-
-volatile int x;
-
-int thread(void *arg) {
-  return (x = 42);
-}
-
-TEST(clone, test) {
-  if (!IsLinux() && !IsNetbsd() && !IsWindows()) return;
-  char *stack;
-  long double t;
-  int tid, ptid, ctid, tls;
-  t = nowl();
-  stack = gc(malloc(FRAMESIZE));
-  EXPECT_NE(-1, (tid = clone(thread, stack + FRAMESIZE,
-                             CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND,
-                             0, &ptid, &tls, &ctid)));
-  while ((nowl() - t) < 1 && !x) {
-    __builtin_ia32_pause();
-  }
-  ASSERT_EQ(42, x);
-}