FTP FEAT error handling

FTP FEAT error handling

Some FTP severs respond to a FEAT command with 5xx status code. Squid sends
an invalid response in these cases which can confuse the client.

This patch fixes Squid to always send a valid 211 reply to client which
lists at least the EPSV and EPRT ftp commands which supported by Squid
regardless of the origin server support.

This patch also fixes a memory leak when FEAT replies processed.

This is a Measurement Factory project