gpg: Fix regression since 2.1 in --search-key with a fingerprint.
* dirmngr/ks-engine-hkp.c (ks_hkp_search): Prefix fingerprint with 0x.
pre-2.1 made sure that the 0x prefix was put before the fingerprint so
that the search command works. Actually --recv-key should be used
with a fingerprint but some users are using --search-key, probably to
use the interactive mode.
- GnuPG-bug-id: T2412
- Signed-off-by: Werner Koch <wk@gnupg.org>