If this option is set, the connection listener sets the close-on-exec
flag on the underlying listener socket. See platform documentation for
fcntl
and
FD_CLOEXEC
for more information.
By default on some platforms, once a listener socket is closed, no
other socket can bind to the same port until a while has passed.
Setting this option makes Libevent mark the socket as reusable, so that
once it is closed, another socket can be opened to listen on the same
port.