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/ip.h

@@ -0,0 +1,45 @@
+#ifndef COSMOPOLITAN_NET_HTTP_IP_H_
+#define COSMOPOLITAN_NET_HTTP_IP_H_
+
+#define kIpUnknown    0
+#define kIpMulticast  1
+#define kIpLoopback   2
+#define kIpPrivate    3
+#define kIpTestnet    4
+#define kIpAfrinic    5
+#define kIpLacnic     6
+#define kIpApnic      7
+#define kIpArin       8
+#define kIpRipe       9
+#define kIpDod        10
+#define kIpAtt        11
+#define kIpApple      12
+#define kIpFord       13
+#define kIpCogent     14
+#define kIpPrudential 15
+#define kIpUsps       16
+#define kIpComcast    17
+#define kIpFuture     18
+#define kIpAnonymous  19
+
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+bool IsDodIp(uint32_t);
+bool IsArinIp(uint32_t);
+bool IsRipeIp(uint32_t);
+bool IsApnicIp(uint32_t);
+bool IsLacnicIp(uint32_t);
+bool IsPublicIp(uint32_t);
+bool IsPrivateIp(uint32_t);
+bool IsAfrinicIp(uint32_t);
+bool IsTestnetIp(uint32_t);
+bool IsLoopbackIp(uint32_t);
+bool IsMulticastIp(uint32_t);
+bool IsAnonymousIp(uint32_t);
+int CategorizeIp(uint32_t);
+const char *GetIpCategoryName(int);
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_NET_HTTP_IP_H_ */