Use %autosetup macro to unpack and patch source
    
    Using %autosetup frees us from having to manage %patch entries.  It does
    require that all patches use the same strip level (-p1 in our case).
    There is also a mildly annoying bug in EL-6¹ which chokes on the patch
    invocation if a blank line doesn't follow %autosetup.  A comment should
    prevent any problems.
    
    The %autosetup -S option is deliberately avoided, to prevent needless
    bootstrapping problems.
    
    ¹ https://bugzilla.redhat.com/1310704