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/intrin/getfileattributes.greg.c

@@ -28,7 +28,7 @@ __msabi extern typeof(GetFileAttributes) *const __imp_GetFileAttributesW;
 /**
  * Gets file info on the New Technology.
  *
- * @return handle, or -1 on failure
+ * @return handle, or -1u on failure
  * @note this wrapper takes care of ABI, STRACE(), and __winerr()
  */
 textwindows uint32_t GetFileAttributes(const char16_t *lpPathName) {