* src/ftp.c (getftp): Do not use PORT when PASV fails.
* tests/FTPServer.px: Add pasv_not_supported server flag.
* tests/Makefile.am: Add Test-ftp-pasv-not-supported.px
* tests/Test-ftp-pasv-not-supported.px: New test
Fix IP address exposure when automatically falling back from
passive mode to active mode (using the PORT command). A behavior that
may be used to expose a client's privacy even when using a proxy.