* Don't send uninitialized data
* Close descriptors more carefully
* Add comments

travis-ci: success for zdtm: improve socket-tcp-close-wait.c
Reported-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>