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/test.mk

@@ -18,6 +18,7 @@ o/$(MODE)/test/libc:					\
 		o/$(MODE)/test/libc/sock		\
 		o/$(MODE)/test/libc/stdio		\
 		o/$(MODE)/test/libc/str			\
+		o/$(MODE)/test/libc/thread		\
 		o/$(MODE)/test/libc/time		\
 		o/$(MODE)/test/libc/tinymath		\
 		o/$(MODE)/test/libc/unicode		\