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/libc/fmt/strerror_test.c

@@ -30,17 +30,14 @@
  */
 
 TEST(strerror, e2big) {
-  if (IsTiny()) return;
   EXPECT_STARTSWITH("E2BIG", strerror(E2BIG));
 }
 
 TEST(strerror, enosys) {
-  if (IsTiny()) return;
   EXPECT_STARTSWITH("ENOSYS", strerror(ENOSYS));
 }
 
 TEST(strerror, einval) {
-  if (IsTiny()) return;
   EXPECT_STARTSWITH("EINVAL", strerror(EINVAL));
 }
 
@@ -50,14 +47,9 @@ TEST(strerror, symbolizingTheseNumbersAsErrorsIsHeresyInUnixStyle) {
 }
 
 TEST(strerror, enotconn_orLinkerIsntUsingLocaleC_orCodeIsOutOfSync) {
-  if (IsTiny()) return;
   EXPECT_STARTSWITH("ENOTCONN", strerror(ENOTCONN));
 }
 
 TEST(strerror, exfull_orLinkerIsntUsingLocaleC_orCodeIsOutOfSync) {
-  if (!IsTiny()) {
-    EXPECT_STARTSWITH("ETXTBSY", strerror(ETXTBSY));
-  } else {
-    EXPECT_STARTSWITH("EUNKNOWN", strerror(ETXTBSY));
-  }
+  EXPECT_STARTSWITH("ETXTBSY", strerror(ETXTBSY));
 }