Its sole remaining purpose was to display "proxy foo started", which
has little benefit and pollutes output for those with plenty of proxies.
Let's remove it now.
The VTCs were updated to reflect this, because many of them had explicit
counts of dropped lines to match this message.
This is tagged as MEDIUM because some users may be surprized by the
loss of this quite old message.
Since the health-check refactoring in the 2.2, the checks through a socks4 proxy
are broken. To fix this bug, CO_FL_SOCKS4 flag must be set on the connection
before calling the connect() callback function because this flags is checked to
use the right destination address. The same is done for the CO_FL_SEND_PROXY
flag for a consistency purpose.
A reg-test has been added to test the "check-via-socks4" directive.
This patch must be backported to 2.2.
