Vendor update hcsshim to v0.5.8

Signed-off-by: Darren Stahl <darst@microsoft.com>

vendor.conf

@@ -1,6 +1,6 @@
 # the following lines are in sorted order, FYI
 github.com/Azure/go-ansiterm 388960b655244e76e24c75f48631564eaefade62
-github.com/Microsoft/hcsshim v0.5.7
+github.com/Microsoft/hcsshim v0.5.8
 github.com/Microsoft/go-winio v0.3.6
 github.com/Sirupsen/logrus f76d643702a30fbffecdfe50831e11881c96ceb3 https://github.com/aaronlehmann/logrus
 github.com/davecgh/go-spew 6d212800a42e8ab5c146b8ace3490ee17e5225f9

vendor/github.com/Microsoft/hcsshim/container.go

@@ -192,6 +192,10 @@ func GetContainers(q ComputeSystemQuery) ([]ContainerProperties, error) {
 	)
 	err = hcsEnumerateComputeSystems(query, &computeSystemsp, &resultp)
 	err = processHcsResult(err, resultp)
+	if err != nil {
+		return nil, err
+	}
+
 	if computeSystemsp == nil {
 		return nil, ErrUnexpectedValue
 	}