Remove OneOfOne xxhash in favor of cespare (elastic#15518)

NOTICE.txt

@@ -4776,16 +4776,6 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 
---------------------------------------------------------------------
-Dependency: github.com/OneOfOne/xxhash
-Version: v1.2.7
-Revision: 85d5025fe15b385888b1886ea99f722f549a6934
-License type (autodetected): Apache-2.0
-./vendor/github.com/OneOfOne/xxhash/LICENSE:
---------------------------------------------------------------------
-Apache License 2.0
-
-
 --------------------------------------------------------------------
 Dependency: github.com/opencontainers/go-digest
 Revision: ac19fd6e7483ff933754af248d80be865e543d22

libbeat/processors/fingerprint/hash.go

@@ -25,7 +25,7 @@ import (
 	"hash"
 	"strings"
 
-	"github.com/OneOfOne/xxhash"
+	"github.com/cespare/xxhash"
 )
 
 type hashMethod func() hash.Hash
@@ -36,7 +36,7 @@ var hashes = map[string]hashMethod{
 	"sha256": sha256.New,
 	"sha384": sha512.New384,
 	"sha512": sha512.New,
-	"xxhash": xxhash.NewHash64,
+	"xxhash": newXxHash,
 }
 
 // Unpack creates the hashMethod from the given string
@@ -51,3 +51,8 @@ func (f *hashMethod) Unpack(str string) error {
 	*f = m
 	return nil
 }
+
+// newXxHash returns a hash.Hash instead of the *Digest which implements the same
+func newXxHash() hash.Hash {
+	return xxhash.New()
+}