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/rename.c

@@ -22,6 +22,12 @@
 /**
  * Moves file the Unix way.
  *
+ * This is generally an atomic operation with the file system, since all
+ * it's doing is changing a name associated with an inode. However, that
+ * means rename() doesn't permit your `oldpathname` and `newpathname` to
+ * be on separate file systems, in which case this returns EXDEV. That's
+ * also the case on Windows.
+ *
  * @return 0 on success or -1 w/ errno
  * @asyncsignalsafe
  */