multisocketsink: fix "client-removed" signal on 64-bit platforms and with bindings
The client-removed signal used G_INT_TYPE instead of G_SOCKET_TYPE in its definition leading to problems on platforms where the size of a pointer is larger than the size of an integer, It would also not work at all with dynamic language bindings. https://bugzilla.gnome.org/show_bug.cgi?id=757155