Update curl example to support ssl / https

Now that we know our SSL client works, and that it's able to verify
certificates, the next step will be adding it as an API to redbean.

See #97

libc/x/xslurp.c

@@ -30,7 +30,7 @@
  * @return NUL-terminated malloc'd contents, or NULL w/ errno
  * @note this is uninterruptible
  */
-char *xslurp(const char *path, size_t *opt_out_size) {
+void *xslurp(const char *path, size_t *opt_out_size) {
   int fd;
   ssize_t rc;
   size_t i, got;