Vendor sirupsen/logrus@1.3.0

Signed-off-by: John Howard <jhoward@microsoft.com>

vendor/github.com/sirupsen/logrus/terminal_check_notappengine.go

@@ -0,0 +1,19 @@
+// +build !appengine,!js,!windows,!aix
+
+package logrus
+
+import (
+	"io"
+	"os"
+
+	"golang.org/x/crypto/ssh/terminal"
+)
+
+func checkIfTerminal(w io.Writer) bool {
+	switch v := w.(type) {
+	case *os.File:
+		return terminal.IsTerminal(int(v.Fd()))
+	default:
+		return false
+	}
+}