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/ubsan.c

@@ -301,7 +301,7 @@ static __ubsan_die_f *__ubsan_type_mismatch_handler(
     p = __stpcpy(p, " align ");
     p = __intcpy(p, info->alignment);
   } else {
-    p = __stpcpy(p, "insufficient size%n\t");
+    p = __stpcpy(p, "insufficient size ");
     p = __stpcpy(p, kind);
     p = __stpcpy(p, " address 0x");
     p = __fixcpy(p, pointer, sizeof(pointer) * CHAR_BIT);