* lang/cpp/src/context.cpp
(Context::setExpire, Context::startSetExpire): New.
(Context::getLFSeparatedListOfFingerprintsFromSubkeys):
New helper.
* lang/cpp/src/context.h
(Context::SetExpireFlags): New enum.
(Context::setExpire, Context::startSetExpire): Add
prototypes.
(Context::getLFSeparatedListOfFingerprintsFromSubkeys):
Add as private helper.