tests: Skip key types not supported by OpenSSH.
* tests/openpgp/ssh-import.scm (path): New variable. (ssh,ssh-keygen,ssh-version,ssh-supports?): Likewise.
Skip algorithms not supported by the OpenSSH in the ssh import test.
This notably fixes the test on macOS when the stock ssh version is
used.
- GnuPG-bug-id: T2947
- Signed-off-by: Justus Winter <justus@g10code.com>