bugfix: default EXPAND-TO-FOREIGN expansion was ignoring secondary value.

Said expansion breaks the protocol between TRANSLATE-TO-FOREIGN and
FREE-TRANSLATED-OBJECT.

This wasn't an issue when using EXPAND-TO-FOREIGN-DYN since it discards
the default expansion of EXPAND-TO-FOREIGN. Only CONVERT-OBJECT-FOREIGN
and DEFCALLBACK call EXPAND-TO-FOREIGN directly and the latter has to
discard the second value anyway.