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

libc/calls/truncate-nt.c

@@ -25,15 +25,17 @@
 #include "libc/nt/runtime.h"
 
 textwindows int sys_truncate_nt(const char *path, uint64_t length) {
+  int rc;
   bool32 ok;
   int64_t fh;
   uint16_t path16[PATH_MAX];
   if (__mkntpath(path, path16) == -1) return -1;
   if ((fh = CreateFile(path16, kNtGenericWrite, kNtFileShareRead, NULL,
                        kNtOpenExisting, kNtFileAttributeNormal, 0)) != -1) {
-    ok = sys_ftruncate_nt(fh, length);
+    rc = sys_ftruncate_nt(fh, length);
     CloseHandle(fh);
-    if (ok) return 0;
+  } else {
+    rc = -1;
   }
-  return __winerr();
+  return __fix_enotdir(rc, path16);
 }