client: Delay additional input processing until after send

client: Delay additional input processing until after send

We need to copy input to @auxfp to implement command line option -2,
and pass it to save_input() to enable protection against a rogue
server exploiting redirection and execute.  We currently do this right
when input enters the ring buffer, in recv_input().

Calling save_input() before sending input to the server is sloppy: it
can make the client accept "future" redirections and executes.

Delay save_input() until after input is sent.  For simplicity, delay
copying to @auxfp as well.

This is actually pretty close to how things worked before commit
8b7d0b9 (v4.3.11).

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>