Fix types of {get,set}SockOptInt in signature SOCKET_EXTRA.CtlExtra.

Commit 00de4e4acaf05c61cfc3a3c1ccfad21eaea1a6d8 (aka, r7612) changed
{get,set}SockOptInt from working with the (platform) C int type to
working with the (default) SML int type.  While those two types are
typically equal, using '-default-type intinf' would lead to a type
error when compiling the Basis Library.
Remove unused specifications from signature SOCKET_EXTRA.CtlExtra.