Add LockTagTypeNames for distributed xid

Commit 13a1f66f forgot to modify the corresponding LockTagTypeNames array. 
This commit fixes this.

src/backend/utils/gdd/gddfuncs.c

@@ -50,6 +50,7 @@ static const char *const LockTagTypeNames[] = {
 	"append-only segment file",
 	"object",
 	"resource queue",
+	"distributed xid",
 	"userlock",
 	"advisory"
 };