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/sig2.c

@@ -149,7 +149,11 @@ static textwindows bool __sig_deliver(bool restartable, int sig, int si_code,
  * Returns true if signal default action is to end process.
  */
 static textwindows bool __sig_isfatal(int sig) {
-  return sig != SIGCHLD;
+  if (sig == SIGCHLD || sig == SIGURG || sig == SIGWINCH) {
+    return false;
+  } else {
+    return true;
+  }
 }
 
 /**