Add HTTP/HTTPS Fetch() API to redbean

You can now say the following in your redbean Lua code:

    status,headers,payload = Fetch("https://foo.example")

The following Lua APIs have been introduced:

  - Fetch(str) → str,{str:str},str
  - GetHttpReason(int) → str
  - GetHttpReason(int) → str
  - ProgramSslFetchVerify(bool)
  - ProgramSslClientVerify(bool)

The following flags have been introduced:

  - `-j` enables client SSL verification
  - `-k` disables Fetch() SSL verification
  - `-t INT` may now be passed a negative value for keepalive

Lua exceptions now invoke Cosmopolitan's garbage collector when
unwinding the stack. So it's now safe to use _gc() w/ Lua 𝔱𝔥𝔯𝔬𝔴

See #97

test/net/http/unchunk_test.c

@@ -17,6 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
 #include "net/http/http.h"
 
 ssize_t EzUnchunk(char *p, size_t n, size_t *l) {