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

third_party/regex/regex.h

@@ -14,8 +14,8 @@ COSMOPOLITAN_C_START_
 #define REG_NEWLINE  4
 #define REG_NOSUB    8
 
-#define REG_NOTBOL 1
-#define REG_NOTEOL 2
+#define REG_NOTBOL 1 /* ^ should not match beginning of string */
+#define REG_NOTEOL 2 /* $ should not match end of string */
 
 #define REG_OK       0
 #define REG_NOMATCH  1
@@ -36,20 +36,20 @@ COSMOPOLITAN_C_START_
 
 typedef long regoff_t;
 
-struct Regex {
+struct PosixRegex {
   size_t re_nsub;
   void *__opaque, *__padding[4];
   size_t __nsub2;
   char __padding2;
 };
 
-struct RegexMatch {
+struct PosixRegexMatch {
   regoff_t rm_so;
   regoff_t rm_eo;
 };
 
-typedef struct Regex regex_t;
-typedef struct RegexMatch regmatch_t;
+typedef struct PosixRegex regex_t;
+typedef struct PosixRegexMatch regmatch_t;
 
 int regcomp(regex_t *, const char *, int);
 int regexec(const regex_t *, const char *, size_t, regmatch_t *, int);