Add --read-only-tmpfs options

The --read-only-tmpfs option caused podman to mount tmpfs on /run, /tmp, /var/tmp
if the container is running int read-only mode.

The default is true, so you would need to execute a command like

--read-only --read-only-tmpfs=false to turn off this behaviour.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

pkg/spec/createconfig.go

@@ -113,6 +113,7 @@ type CreateConfig struct {
 	PublishAll         bool     //publish-all
 	Quiet              bool     //quiet
 	ReadOnlyRootfs     bool     //read-only
+	ReadOnlyTmpfs      bool     //read-only-tmpfs
 	Resources          CreateResourceConfig
 	Rm                 bool              //rm
 	StopSignal         syscall.Signal    // stop-signal