Make all Protocol* constants typed, not just the first one.
Make all Protocol* constants typed, not just the first one.

The type is set per ConstSpec, not inherited like iota.

(This should be ultimately done for all constants; this commit only
handles Protocol.)

cortex/gpgme,cortex/gpgme,mtrmac/gpgme,proglottis/gpgme,mtrmac/gpgme,proglottis/gpgme