[VOL-5486] Fix deprecated versions

Change-Id: I3e03ea246020547ae75fa92ce8cf5cbba7e8f3bb
Signed-off-by: Abhay Kumar <abhay.kumar@radisys.com>
diff --git a/vendor/github.com/prometheus/common/model/signature.go b/vendor/github.com/prometheus/common/model/signature.go
index 8762b13..dc8a002 100644
--- a/vendor/github.com/prometheus/common/model/signature.go
+++ b/vendor/github.com/prometheus/common/model/signature.go
@@ -22,10 +22,8 @@
 // when calculating their combined hash value (aka signature aka fingerprint).
 const SeparatorByte byte = 255
 
-var (
-	// cache the signature of an empty label set.
-	emptyLabelSignature = hashNew()
-)
+// cache the signature of an empty label set.
+var emptyLabelSignature = hashNew()
 
 // LabelsToSignature returns a quasi-unique signature (i.e., fingerprint) for a
 // given label set. (Collisions are possible but unlikely if the number of label