Port autoselection done by kernel only works when number of bound
sockets is under a threshold (typically 30000).

When this threshold is over, we must check if there is a conflict before
exiting first loop in inet_csk_get_port()

Change inet_csk_bind_conflict() to forbid two reuse-enabled sockets to
bind on same (address,port) tuple (with a non ANY address)

Same change for inet6_csk_bind_conflict()
Reported-by: NGaspar Chilingarov <gasparch@gmail.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>