Add the generated flatfs stub, since it cannot be auto-generated

fuzz/go.mod

@@ -6,5 +6,6 @@ replace github.com/ipfs/go-datastore => ../
 
 require (
 	github.com/ipfs/go-datastore v0.4.4
+	github.com/ipfs/go-ds-flatfs v0.4.4
 	github.com/spf13/pflag v1.0.3
 )

fuzz/go.sum

@@ -2,6 +2,7 @@ github.com/AndreasBriese/bbloom v0.0.0-20190306092124-e2d15f34fcf9 h1:HD8gA2tkBy
 github.com/AndreasBriese/bbloom v0.0.0-20190306092124-e2d15f34fcf9/go.mod h1:bOvUY6CB00SOBii9/FifXqc0awNKxLFCL/+pkDPuyl8=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
+github.com/alexbrainman/goissue34681 v0.0.0-20191006012335-3fc7a47baff5 h1:iW0a5ljuFxkLGPNem5Ui+KBjFJzKg4Fv2fnxe4dvzpM=
 github.com/alexbrainman/goissue34681 v0.0.0-20191006012335-3fc7a47baff5/go.mod h1:Y2QMoi1vgtOIfc+6DhrMOGkLoGzqSV2rKp4Sm+opsyA=
 github.com/armon/consul-api v0.0.0-20180202201655-eb2c6b5be1b6/go.mod h1:grANhF5doyWs3UAsr3K4I6qtAmlQcZDesFNEHPZAzj8=
 github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=

fuzz/provider_go-ds-flatfs.go

+package fuzzer
+
+import (
+	ds "github.com/ipfs/go-datastore"
+	prov "github.com/ipfs/go-ds-flatfs"
+)
+
+func init() {
+	AddOpener("go-ds-flatfs", func(loc string) ds.Datastore {
+		d, err := prov.CreateOrOpen(loc, prov.IPFS_DEF_SHARD, false)
+		if err != nil {
+			panic("could not create db instance")
+		}
+		return d
+	})
+}