Allow disabling inheriting ExcludeArch to noarch packages
    
    Copying ExcludeArch/ExclusiveArch from source rpm to noarch is an easy
    option to block shipping that particular noarch package from a certain
    architecture. However, there is no way to bypass it, and it is rather
    confusing and not discoverable.
    
    An alternative way to remove an unwanted package is to use the good old
    `filter_packages`, which has enough granularity to remove pretty much
    anything from anywhere. The only downside is that it requires a change
    in configuration, so it can't be done by a packager directly from a spec
    file.
    
    When we decide to break backwards compatibility, this option should be
    removed and the entire ExcludeArch/ExclusiveArch inheritance removed
    completely.
    
    JIRA: ENGCMP-2606
    Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>