* dtable.cc (dtable::release): Check for socket. Change

    * dtable.cc (dtable::release): Check for socket. Change
        cnt_need_fixup_before accordingly.
        (dtable::dup2): Ditto.
        (dtable::fixup_before_fork): New method.
        (dtable::fixup_before_exec): Ditto.
        * dtable.h (class dtable): Add member `cnt_need_fixup_before'. Add
        definition for methods `dec_need_fixup_before', `inc_need_fixup_before',
        `need_fixup_before', `fixup_before_exec' and `fixup_before_fork'.
        * fhandler.h (class fhandler_base): Slight rearrangements. Add
        definitions for methods `fixup_before_fork_exec'.
        (class fhandler_socket): Eliminate superfluous constructor.
        Add member `prot_info_ptr'. Add destructor. Add definitions for
        methods `dup', `fixup_before_fork_exec', `fixup_after_fork' and
        `fixup_after_exec'.
        * fork.cc (fork_parent): Care for file types which need a fixup
        before fork. Start child in suspended state then.
        * net.cc: New global variable `ws2_32_handle' and `wsadata'.
        (fdsock): Check for Winsock version. Call `set_socket_inheritance'
        only if Winsock version < 2.0. Care for `need_fixup' count in fdtab.
        (cygwin_socket): Eliminate call to `set_socket_inheritance'.
        (cygwin_accept): Ditto.
        (cygwin_rcmd): Ditto.
        (cygwin_rresvport): Ditto.
        (cygwin_rexec): Ditto.
        (socketpair): Ditto.
        (fhandler_socket::fhandler_socket): Set `need_fork_fixup'. Allocate
        space for the WSAPROTOCOL_INFOA struct used in fixup.
        (fhandler_socket::~fhandler_socket): New destructor.
        (fhandler_socket::fixup_before_fork_exec): New method.
        (fhandler_socket::fixup_after_fork): Ditto.
        (fhandler_socket::dup): Ditto.
        (wsock_init): New static function.
        (LoadDLLinitfunc (wsock32)): Rearranged.
        (LoadDLLinitfunc (ws2_32)): New function.
        (dummy_autoload): Add autoload statemants for `WSADuplicateSocketA'
        and `WSASocketA'.
        * spawn.cc (spawn_guts): Care for file types which need a fixup
        before exec. Start child in suspended state then.