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

tool/net/redbean-form.lua

@@ -17,9 +17,9 @@ local function main()
    lastname = GetParam('lastname')
    if firstname and lastname then
       Write('Hello ')
-      Write(EscapeHtml(firstname))
+      Write(EscapeHtml(VisualizeControlCodes(firstname)))
       Write(' ')
-      Write(EscapeHtml(lastname))
+      Write(EscapeHtml(VisualizeControlCodes(lastname)))
       Write('!<br>')
       Write('Thank you for using redbean.')
    end
@@ -32,11 +32,11 @@ local function main()
    params = GetParams()
    for i = 1,#params do
       Write('<dt>')
-      Write(EscapeHtml(params[i][1]))
+      Write(EscapeHtml(VisualizeControlCodes(params[i][1])))
       Write('\r\n')
       if params[i][2] then
          Write('<dd>')
-         Write(EscapeHtml(params[i][2]))
+         Write(EscapeHtml(VisualizeControlCodes(params[i][2])))
          Write('\r\n')
       end
    end
@@ -57,7 +57,7 @@ local function main()
 
    Write('<dt>Payload\r\n')
    Write('<dd><p>')
-   Write(EscapeHtml(GetPayload()))
+   Write(EscapeHtml(VisualizeControlCodes(GetPayload())))
    Write('\r\n')
 
    Write('</dl>\r\n')