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/parseurl_test.c

@@ -22,6 +22,7 @@
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/hyperion.h"
 #include "libc/testlib/testlib.h"
+#include "net/http/http.h"
 #include "net/http/url.h"
 
 TEST(ParseUrl, testEmpty) {
@@ -160,8 +161,7 @@ TEST(ParseUrl, testUrl) {
   ASSERT_EQ('b', h.user.p[0]);
   ASSERT_EQ(1, h.pass.n);
   ASSERT_EQ('B', h.pass.p[0]);
-  ASSERT_EQ(1, h.host.n);
-  ASSERT_EQ('c', h.host.p[0]);
+  ASSERT_STREQ("c", gc(strndup(h.host.p, h.host.n)));
   ASSERT_EQ(1, h.port.n);
   ASSERT_EQ('C', h.port.p[0]);
   ASSERT_EQ(2, h.path.n);
@@ -380,6 +380,16 @@ TEST(ParseHost, testObviouslyIllegalIpLiteral_getsTreatedAsRegName) {
   ASSERT_STREQ("//vf.%3A%3A1%00", gc(EncodeUrl(&h, 0)));
 }
 
+TEST(ParseHost, testUnclosedIpv6_doesntSetPort) {
+  struct Url h = {0};
+  gc(ParseHost("2001:db8:cafe::17", -1, &h));
+  gc(h.params.p);
+  ASSERT_STREQ("2001:db8:cafe::17", gc(strndup(h.host.p, h.host.n)));
+  ASSERT_EQ(0, h.port.n);
+  ASSERT_EQ(0, h.port.p);
+  ASSERT_STREQ("//2001%3Adb8%3Acafe%3A%3A17", gc(EncodeUrl(&h, 0)));
+}
+
 TEST(EncodeUrl, testHostPortPlacedInHostField_ungoodIdea) {
   struct Url h = {0};
   h.host.n = strlen("foo.example:80");
@@ -696,6 +706,8 @@ BENCH(ParseUrl, bench) {
              free(ParseUrl("a://b@c/?zd#f", -1, &h));
              free(h.params.p);
            }));
+  EZBENCH2("ParseHost", donothing, free(ParseHost("127.0.0.1:34832", 15, &h)));
+  EZBENCH2("ParseIp", donothing, ParseIp("127.0.0.1", 9));
 }
 
 BENCH(EncodeUrl, bench) {