* src/CMakeLists.txt (Gpgmepp_SOURCES): Remove trustitem.cpp.
(Gpgmepp_HEADERS): Remove trustitem.h.
* src/context.cpp, src/context.h (class Context): Remove member
functions startTrustItemListing, nextTrustItem, endTrustItemListing.
* src/context_p.h (enum Context::Private::Operation): Remove value
TrustList.
* src/eventloopinteractor.cpp (EventLoopInteractor::Private::eventIOCb):
Remove handling of event GPGME_EVENT_NEXT_TRUSTITEM.
* src/eventloopinteractor.h (EventLoopInteractor): Remove pure virtual
nextTrustItemEvent.
* src/trustitem.cpp, src/trustitem.h: Remove files.

This never worked in reality because the required feature has been
removed from GnuPG version 1.3.2 soon after introduction of this
feature in gpgme in 2003. It was anyway marked as experimental.