Re-added mount_*.go in docker package to not break tests/build

mount_darwin.go

@@ -0,0 +1,7 @@
+package docker
+
+import "errors"
+
+func mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
+	return errors.New("mount is not implemented on darwin")
+}

mount_linux.go

@@ -0,0 +1,8 @@
+package docker
+
+import "syscall"
+
+
+func mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
+	return syscall.Mount(source, target, fstype, flags, data)
+}