Ported the "latest" YMFM changes.

To 86box.

src/sound/ymfm/ymfm.h

@@ -485,6 +485,8 @@ public:
 class ymfm_engine_callbacks
 {
 public:
+    virtual ~ymfm_engine_callbacks() = default;
+
 	// timer callback; called by the interface when a timer fires
 	virtual void engine_timer_expired(uint32_t tnum) = 0;
 
@@ -506,6 +508,7 @@ class ymfm_interface
 	template<typename RegisterType> friend class fm_engine_base;
 
 public:
+	virtual ~ymfm_interface() = default;
 	// the following functions must be implemented by any derived classes; the
 	// default implementations are sufficient for some minimal operation, but will
 	// likely need to be overridden to integrate with the outside world; they are

src/sound/ymfm/ymfm_fm.ipp

@@ -1518,7 +1518,7 @@ void fm_engine_base<RegisterType>::engine_timer_expired(uint32_t tnum)
 		for (uint32_t chnum = 0; chnum < CHANNELS; chnum++)
 			if (bitfield(RegisterType::CSM_TRIGGER_MASK, chnum))
 			{
-				m_channel[chnum]->keyonoff(1, KEYON_CSM, chnum);
+				m_channel[chnum]->keyonoff(0xf, KEYON_CSM, chnum);
 				m_modified_channels |= 1 << chnum;
 			}
 

src/sound/ymfm/ymfm_ssg.h

@@ -49,6 +49,8 @@ namespace ymfm
 class ssg_override
 {
 public:
+	virtual ~ssg_override() = default;
+
 	// reset our status
 	virtual void ssg_reset() = 0;