Struct members, including command arguments, event data, and union
inline base members, should use '-', not '_'.  Enforce this.  Fix the
fixable offenders (all in tests/), and add the remainder to pragma
member-name-exceptions.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210323094025.3569441-27-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>