[go/fixchain] updated x509 lib doesn't return duplicate roots

The Go 1.8 library will no longer return a chain with a duplicated root
at the end (like Leaf -> Int -> RootA -> RootA).
golang/go@07a31bc3da11

Author: daviddrysdale

go/fixchain/fix_test.go

@@ -27,7 +27,6 @@ var constructChainTests = []fixTest{
 		function: "constructChain",
 		expectedChains: [][]string{
 			{"Leaf", "Intermediate2", "Intermediate1", "CA"},
-			{"Leaf", "Intermediate2", "Intermediate1", "CA", "CA"},
 		},
 	},
 	{ // No roots results in an error