stdio connected UI: drop perl prototype definitions

stdio connected UI: drop perl prototype definitions

The prototypes where completely circumvented by calling those two
methods by reference via &, and that probably happened as the send_msg
one was just wrong, it forced scalar context for the second parameter,
while that was a list (or well hash, but the difference there can be
blurry).

Anyhow, prototypes are not always of help, and can be a PITA with
side-effects too, and especially for such small modules it has not
that much use to declare them for privately-scoped methods, so just
drop them and fix the calling style.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>