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

test/net/http/escapejsstringliteral_test.c

@@ -24,10 +24,11 @@
 #include "net/http/escape.h"
 
 char *escapejs(const char *s) {
-  struct EscapeResult r;
-  r = EscapeJsStringLiteral(s, strlen(s));
-  ASSERT_EQ(strlen(r.data), r.size);
-  return r.data;
+  char *p;
+  size_t n;
+  p = EscapeJsStringLiteral(s, strlen(s), &n);
+  ASSERT_EQ(strlen(p), n);
+  return p;
 }
 
 TEST(EscapeJsStringLiteral, test) {
@@ -53,27 +54,29 @@ TEST(EscapeJsStringLiteral, testBrokenUnicode_sparesInnocentCharacters) {
 
 void makefile1(void) {
   FILE *f;
-  struct EscapeResult r;
-  r = EscapeJsStringLiteral(kHyperion, kHyperionSize);
+  char *p;
+  size_t n;
+  p = EscapeJsStringLiteral(kHyperion, kHyperionSize, &n);
   f = fopen("/tmp/a", "wb");
-  fwrite(r.data, r.size, 1, f);
+  fwrite(p, n, 1, f);
   fclose(f);
-  free(r.data);
+  free(p);
 }
 
 void makefile2(void) {
   int fd;
-  struct EscapeResult r;
-  r = EscapeJsStringLiteral(kHyperion, kHyperionSize);
+  char *p;
+  size_t n;
+  p = EscapeJsStringLiteral(kHyperion, kHyperionSize, &n);
   fd = creat("/tmp/a", 0644);
-  write(fd, r.data, r.size);
+  write(fd, p, n);
   close(fd);
-  free(r.data);
+  free(p);
 }
 
 BENCH(EscapeJsStringLiteral, bench) {
   EZBENCH2("escapejs", donothing,
-           free(EscapeJsStringLiteral(kHyperion, kHyperionSize).data));
+           free(EscapeJsStringLiteral(kHyperion, kHyperionSize, 0)));
   EZBENCH2("makefile1", donothing, makefile1());
   EZBENCH2("makefile2", donothing, makefile2());
 }