keyboxd: Fix searching for exact mail addresses.

* kbx/kbxserver.c (cmd_search): Use the openpgp hack for calling
classify_user_id.
* kbx/backend-sqlite.c (run_select_statement): Remove angle brackets
in exact addrspec mode.
* g10/call-keyboxd.c (keydb_search): Do not duplicate the left angle
bracket.
* sm/keydb.c (keydb_search): Ditto.

Note that the openpgp hack flag of classify_user_id is actually a
misnomer because we actually hack a round a problem in gpgsm. And it
is only over there that we don't set it there. In keyboxd the flag
should be set. And we need to remove the angle brackets of course
because that is how we create the addrspec column values.

• Signed-off-by: Werner Koch <wk@gnupg.org>