Turn off W+X warnings (rhbz 1306885)
    
    The W+X warning is useful for finding potentially insecure
    mappings. Fixes for some of the warning have stalled leading
    to lots of reports of warnings though. There isn't much use
    for this in stable releases since any fix will be trickling
    in through rawhide anyway. Turn it off for stable releases
    and leave it on for rawhide.