tcpsvd: don't keep shared fd open if fd limit is reached. closes 9331

Also, much improved help text.

function                                             old     new   delta
packed_usage                                       30652   30851    +199
tcpudpsvd_main                                      1782    1784      +2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1 file changed