Add /statusz page to redbean plus other enhancements

redbean improvements:

- Explicitly disable corking
- Simulate Python regex API for Lua
- Send warmup requests in main process on startup
- Add Class-A granular IPv4 network classification
- Add /statusz page so you can monitor your redbean's health
- Fix regressions on OpenBSD/NetBSD caused by recent changes
- Plug Authorization header into Lua GetUser and GetPass APIs
- Recognize X-Forwarded-{For,Host} from local reverse proxies
- Add many additional functions to redbean Lua server page API
- Report resource usage of child processes on `/` listing page
- Introduce `-a` flag for logging child process resource usage
- Introduce `-t MILLIS` flag and `ProgramTimeout(ms)` init API
- Introduce `-H "Header: value"` flag and `ProgramHeader(k,v)` API

Cosmopolitan Libc improvements:

- Make strerror() simpler
- Make inet_pton() not depend on sscanf()
- Fix OpenExecutable() which broke .data section earlier
- Fix stdio in cases where it overflows kernel tty buffer
- Fix bugs in crash reporting w/o .com.dbg binary present
- Add polyfills for SO_LINGER, SO_RCVTIMEO, and SO_SNDTIMEO
- Polyfill TCP_CORK on BSD and XNU using TCP_NOPUSH magnums

New netcat clone in examples/nc.c:

While testing some of the failure conditions for redbean, I noticed that
BusyBox's `nc` command is pretty busted, if you use it as an interactive
tool, rather than having it be part of a pipeline. Unfortunately this'll
only work on UNIX since Windows doesn't let us poll on stdio and sockets
at the same time because I don't think they want tools like this running
on their platform. So if you want forbidden fruit, it's here so enjoy it

net/http/escapeurl.c

@@ -26,7 +26,10 @@
  * This function is agnostic to the underlying charset.
  * Always using UTF-8 is a good idea.
  *
- * @param size if -1 implies strlen
+ * @param p is input value
+ * @param n if -1 implies strlen
+ * @param z if non-NULL receives output length
+ * @return allocated NUL-terminated buffer, or NULL w/ errno
  * @see kEscapeAuthority
  * @see kEscapeIpLiteral
  * @see kEscapePath
@@ -34,16 +37,17 @@
  * @see kEscapeParam
  * @see kEscapeFragment
  */
-struct EscapeResult EscapeUrl(const char *data, size_t size,
-                              const char xlat[hasatleast 256]) {
+char *EscapeUrl(const char *p, size_t n, size_t *z, const char T[256]) {
+  char *r, *q;
   struct UrlView v;
-  struct EscapeResult r;
-  if (size == -1) size = data ? strlen(data) : 0;
-  v.p = data;
-  v.n = size;
-  r.data = xmalloc(size * 6 + 1);
-  r.size = EscapeUrlView(r.data, &v, xlat) - r.data;
-  r.data = xrealloc(r.data, r.size + 1);
-  r.data[r.size] = '\0';
+  if (n == -1) n = p ? strlen(p) : 0;
+  if (z) *z = 0;
+  if ((q = r = malloc(n * 6 + 1))) {
+    v.p = p, v.n = n;
+    q = EscapeUrlView(r, &v, T);
+    if (z) *z = q - r;
+    *q++ = '\0';
+    if ((q = realloc(r, q - r))) r = q;
+  }
   return r;
 }