[zendframework/zf2#4897] Fix condition
[zendframework/zf2#4897] Fix condition

- If the CURLOPT_INFILESIZE option *is* available, but no content-length
  header is sent, we can proceed. Only reset the CURLOPT_INFILESIZE if
  the content-length header is present.

malinink/zend-http,netroby/zend-http,Maks3w/zend-http,weierophinney/zend-http,zendframework/zend-http,asgrim/zend-http