gpg: Cleanup of the local function key_byname.
* g10/keydb.h (GETKEY_WANT_SECRET): New. (GETKEY_WITH_UNUSABLE): New. * g10/getkey.c (key_byname): Repalce args want_secret and include_unusable by an arg flags. Change the fucntion and all direc callers to use these flags.
This will eventually allow us to add other flags.