fix '+' unescape logic for URI-encoded POST data

git-svn-id: https://gnunet.org/svn/libmicrohttpd@34310 140774ce-b5e7-0310-ab8b-a85725594a96
-bump

git-svn-id: https://gnunet.org/svn/libmicrohttpd@34311 140774ce-b5e7-0310-ab8b-a85725594a96