gpgsm: Fix the compatibility flag de-vs-trustlist.

* sm/call-agent.c (istrusted_status_cb): Cache the de_vs flag when set
through a compatibility flag.

Before copying the trustlist flags into the cache of the current list
item the cache has to be checked for the de_vs flag which was set by
the --compatibility-flags option. If the flag was set by the option it
has to be copied into the cache again.