Make improvements

- Get threads working on NetBSD
- Get threads working on OpenBSD
- Fix Emacs config for Emacs v28
- Improve --strace logging of sigset_t
- Improve --strace logging of struct stat
- Improve memory safety of DescribeThing functions
- Refactor auto stack allocation into LIBC_RUNTIME
- Introduce shell.com example which works on Windows
- Refactor __strace_thing into DescribeThing functions
- Document the CHECK macros and improve them in NDEBUG mode
- Rewrite MAP_STACK so it uses FreeBSD behavior across platforms
- Deprecate and discourage the use of MAP_GROWSDOWN (it's weird)

third_party/linenoise/linenoise.c

@@ -140,7 +140,6 @@
 #include "libc/errno.h"
 #include "libc/fmt/conv.h"
 #include "libc/intrin/asan.internal.h"
-#include "libc/intrin/kprintf.h"
 #include "libc/intrin/nomultics.internal.h"
 #include "libc/log/check.h"
 #include "libc/log/log.h"
@@ -2498,7 +2497,7 @@ char *linenoiseWithHistory(const char *prompt, const char *prog) {
   fflush(stdout);
   if ((path = linenoiseGetHistoryPath(prog))) {
     if (linenoiseHistoryLoad(path) == -1) {
-      kprintf("%r%s: failed to load history: %m%n", path);
+      fprintf(stderr, "%s: failed to load history: %m\n", path);
       free(path);
       path = 0;
     }

third_party/make/job.c

@@ -1485,7 +1485,7 @@ load_too_high (void)
             }
         }
 
-      /* If we got here, something went wrong.  Give up on this method.  */
+      /* If we 𝑔𝑜𝑡 𝑕𝑒𝑟𝑒, something went wrong.  Give up on this method.  */
       if (r < 0)
         DB (DB_JOBS, ("Failed to read " LOADAVG ": %s\n", strerror (errno)));