g10: Fix iteration over getkey results.
* g10/getkey.c (getkey_next): Only ask 'lookup' for the exact match if our caller requested the key. Fixes a crash in 'lookup'.
- GnuPG-bug-id: T2848
- Fixes-commit: 1d03cc77e1706f7da653153ad4b58c61e4fd2573
- Signed-off-by: Justus Winter <justus@g10code.com>