storage: filesystem, add PackfileIter benchmark reading object content
storage: filesystem, add PackfileIter benchmark reading object content

Signed-off-by: Miguel Molina <75004f149038473757da0be07ef76dd4a9bdbc8d@erizocosmi.co>

src-d/go-git,src-d/go-git,go-git/go-git,mcuadros/go-git,go-git/go-git,mcuadros/go-git