3238809 Define %{_module_context} and %{disttag}

Authored and Committed by Petr Šabata 5 years ago
    Define %{_module_context} and %{disttag}
    
    No reason to hide module context from the consumers, plus it's useful to
    keep it in the DISTTAG tag (not to be confused with the %{dist} tag) for
    tracking.
    
    The %{disttag} feature will do nothing until RPM supports it.  This is
    planned in 4.14.2.
    
    See https://bugzilla.redhat.com/show_bug.cgi?id=1596192.
    
    Signed-off-by: Petr Šabata <contyk@redhat.com>