agent: Write both ssh fingerprints to 'sshcontrol' file.
* agent/command-ssh.c (add_control_entry): Hand in the key, write both the MD5- and the SHA256-based fingerprint to the 'sshcontrol' file when adding ssh keys. (ssh_identity_register): Adapt callsite.
- GnuPG-bug-id: T2106
- Signed-off-by: Justus Winter <justus@g10code.com>