Fix ssl:transport_accept/2 to handle socket close

[Rory Byrne]

Hello,

  git fetch git://github.com/jinsky/otp.git ssl_transport_accept_fix

A badmatch exception is thrown from ssl:transport_accept/2 when
ssl:close/1 is called on the socket. This fixes it to return
{error,closed}.

Cheers,

Rory