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/parsehttprequest.c

@@ -60,14 +60,24 @@ void DestroyHttpRequest(struct HttpRequest *r) {
  * that fragmented messages can be handled efficiently. A limitation on
  * message size is imposed to make the header data structures smaller.
  *
+ * This parser assumes ISO-8859-1 and guarantees no C0 or C1 control
+ * codes are present in message fields, with the exception of tab.
+ * Please note that fields like URI may use UTF-8 percent encoding. This
+ * parser doesn't care if you choose ASA X3.4-1963 or MULTICS newlines.
+ *
  * kHttpRepeatable defines which standard header fields are O(1) and
  * which ones may have comma entries spilled over into xheaders. For
  * most headers it's sufficient to simply check the static slice. If
  * r->headers[kHttpFoo].a is zero then the header is totally absent.
  *
- * This parser takes about 300 nanoseconds (900 cycles) to parse a 403
- * byte Chrome HTTP request under MODE=rel on a Core i9 which is about
- * gigabyte per second of throughput per core.
+ * This parser has linear complexity. Each character only needs to be
+ * considered a single time. That's the case even if messages are
+ * fragmented. If a message is valid but incomplete, this function will
+ * return zero so that it can be resumed as soon as more data arrives.
+ *
+ * This parser takes about 500 nanoseconds to parse a 403 byte Chrome
+ * HTTP request under MODE=rel on a Core i9 which is about three cycles
+ * per byte or a gigabyte per second of throughput per core.
  *
  * @note we assume p points to a buffer that has >=SHRT_MAX bytes
  * @see HTTP/1.1 RFC2616 RFC2068