Fix use after free in Curl object's HTTPPOST setopt with unicode FORM_BUFFERPTR.
Fix use after free in Curl object's HTTPPOST setopt with unicode FORM_BUFFERPTR.

Fixes use after free in the Curl object's HTTPPOST setopt when a unicode value
is passed as a value with a FORM_BUFFERPTR. The str object created from
the passed in unicode object would have its buffer used but the unicode object
would be stored instead of the str object.

pycurl/pycurl,pycurl/pycurl,pycurl/pycurl