Add a checkTerminal for nacl to support running on play.golang.org

terminal_check_nacl.go

@@ -0,0 +1,11 @@
+// +build nacl
+
+package logrus
+
+import (
+	"io"
+)
+
+func checkIfTerminal(w io.Writer) bool {
+	return false
+}

terminal_check_notappengine.go

@@ -1,4 +1,4 @@
-// +build !appengine,!js,!windows
+// +build !appengine,!js,!windows,!nacl
 
 package logrus