char: fix waiting for TLS and telnet connection

Since commit d7a04fd7d5008, tcp_chr_wait_connected() was introduced,
so vhost-user could wait until a backend started successfully. In
vhost-user case, the chr socket must be plain unix, and the chr+vhost
setup happens synchronously during qemu startup.

However, with TLS and telnet socket, initial socket setup happens
asynchronously, and s->connected is not set after the socket is
accepted. In order for tcp_chr_wait_connected() to not keep accepting
new connections and proceed with the last accepted socket, it can
check for s->ioc instead.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20160816083332.15088-1-marcandre.lureau@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
