fix POST data not working without string literals

https://curl.se/libcurl/c/curl_easy_setopt.html

Strings passed to libcurl as 'char *' arguments, are copied by the library; the string storage associated to the pointer argument may be discarded or reused after curl_easy_setopt returns. The only exception to this rule is really CURLOPT_POSTFIELDS

ffi.bqn

@@ -62,6 +62,7 @@ curlOptions←{
 
   # long integer options
   postfieldsize⇐60  # size of the POST input data
+  copypostfields⇐10165 # copy POST input data
   timeout⇐78  # timeout in seconds
   timeoutms⇐155  # timeout in milliseconds