Add rawhide upstream sync script
    
    Usage:
    
    1. Invoke the script as follows:
    
           ./sync-upstream.sh upstream-repo
    
       where upstream-repo is the path to the synced upstream git repo.
    
    2. Watch the script run.  If it proceeds to building the package, then
       everything seems good and you just need to test the build after it
       is complete.  If it exits before the build (you'll know if you read
       the output of the script) then manual intervention is required to
       complete the sync.  This will typically happen when a patch fails
       to apply on the new sources.