gpg: Workaround for junk after --trusted-key.

* g10/trust.c (register_trusted_key): Cut off everthing starting as a
hash sign.

This problem is fallout from
commit f99830b72812395da5451152bdd2f2d90a7cb7fb
which fixes

The same could happen with other options taking keyids but we won't
change that because a trailing '#' does not indicate a comment. So
this is really only a workaround and eventually we will
deprecate --trusted-key anyway or require a fingerprint as a value.

• GnuPG-bug-id: T1206
• Signed-off-by: Werner Koch <wk@gnupg.org>