Fix sparse file copying.
Fix sparse file copying.

As pointed out by Ruslan Lutsenko (spil-ruslan),
you can't annotate \0 with r during copyfile_sparse.
That makes the sparseness go away.  Fix that here.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@gmail.com>

moofrank/oz,nullr0ute/oz,imcleod/oz,ndonegan/oz,clalancette/oz,imcleod/oz,mgagne/oz,cernops/oz,NeilBryant/oz,cernops/oz,nullr0ute/oz,NeilBryant/oz,moofrank/oz,mgagne/oz,clalancette/oz,ndonegan/oz