Use new upstream tarball, backport relevant upstream fixes up to commit b688c65
    
    The new tarball hosted on GitHub is not identical to the original one, but
    contains no functional differences
    
    All of Fedora's patches to sysfsutils 2.1.0 have been merged upstream and will
    be included in the next sysfsutils release. This commit incorporates all previous
    patches. Additionally, it backports various fixes added upstream, that mainly
    deal with compiler warnings when using moden compilers.