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/parseurl.c

@@ -127,25 +127,28 @@ static bool ParseScheme(struct UrlParser *u, struct Url *h) {
 }
 
 static void ParseAuthority(struct UrlParser *u, struct Url *h) {
-  bool b = false;
+  int t = 0;
   const char *c = NULL;
   while (u->i < u->size) {
     u->c = u->data[u->i++] & 0xff;
     if (u->c == '/' || u->c == '#' || u->c == '?') {
       break;
     } else if (u->c == '[') {
-      b = true;
+      t = -1;
     } else if (u->c == ']') {
-      b = false;
-    } else if (u->c == ':' && !b) {
+      t = 0;
+    } else if (u->c == ':' && t >= 0) {
+      *u->p++ = ':';
       c = u->p;
+      ++t;
     } else if (u->c == '@') {
       if (c) {
         h->user.p = u->q;
-        h->user.n = c - u->q;
+        h->user.n = c - 1 - u->q;
         h->pass.p = c;
         h->pass.n = u->p - c;
         c = NULL;
+        t = 0;
       } else {
         h->user.p = u->q;
         h->user.n = u->p - u->q;
@@ -159,9 +162,9 @@ static void ParseAuthority(struct UrlParser *u, struct Url *h) {
       *u->p++ = u->c;
     }
   }
-  if (c) {
+  if (t == 1) {
     h->host.p = u->q;
-    h->host.n = c - u->q;
+    h->host.n = c - 1 - u->q;
     h->port.p = c;
     h->port.n = u->p - c;
     c = NULL;