Fix broken -devel package requires
    
    Commit 47eb12c67d1d19bfdc12b347ee2176050c3f7126 added %{epoch} to the -devel
    package requires. As epoch isn't actually defined for this package, this led to
    rpm putting %{epoch} unexpanded in the requires.
    
    ERROR with transaction check vs depsolve:
    libhif(x86-64) = %{epoch}:0.1.8-6.fc23 is needed by libhif-devel-0.1.8-6.fc23.x86_64