curl - security update

Symeon Paraschoudis discovered that the curl_easy_duphandle() function
in cURL, an URL transfer library, has a bug that can lead to libcurl
eventually sending off sensitive data that was not intended for sending,
while performing a HTTP POST operation.

This bug requires CURLOPT_COPYPOSTFIELDS and curl_easy_duphandle() to be
used in that order, and then the duplicate handle must be used to
perform the HTTP POST. The curl command line tool is not affected by
this problem as it does not use this sequence.

For Debian 6 Squeeze, these issues have been fixed in curl version 7.21.0-2.1+squeeze10