Prepare boltutil for reading and writing another map
Prepare boltutil for reading and writing another map

Refactor the code so that another function can also read and write maps
into the bolt db.

Signed-off-by: Stefan Berger <5c96973112e540fb909b13997fcd087e5bfbee96@linux.ibm.com>

vdemeester/containerd,thaJeztah/containerd,containerd/containerd,crosbymichael/containerd,crosbymichael/containerd,dmcgowan/containerd,containerd/containerd,mikebrow/containerd,estesp/containerd,thaJeztah/containerd,dmcgowan/containerd,mikebrow/containerd,estesp/containerd,vdemeester/containerd