Make sure digit events are not reported as "ERROR"

dahdievent_to_analogevent used a simple switch statement to convert DAHDI
event numbers to "ANALOG_*" event numbers. However "digit" events
(DAHDI_EVENT_PULSEDIGIT, DAHDI_EVENT_DTMFDOWN, DAHDI_EVENT_DTMFUP)
are accompannied by the digit in the low word of the event number.

This fix makes dahdievent_to_analogevent() return the event number as-is
for such an event.

This is also required to fix #15924 (in addition to r222108).  


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@222237 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_dahdi.c

@@ -2457,6 +2457,17 @@ static enum analog_event dahdievent_to_analogevent(int event)
 		res = ANALOG_EVENT_DTMFUP;
 		break;
 	default:
+		switch(event & 0xFFFF0000) {
+		case DAHDI_EVENT_PULSEDIGIT:
+		case DAHDI_EVENT_DTMFDOWN:
+		case DAHDI_EVENT_DTMFUP:
+			/* The event includes a digit number in the low word.
+			 * Converting it to a 'enum analog_event' would remove
+			 * that information. Thus it is returned as-is.
+			 */
+			return event;
+		}
+
 		res = ANALOG_EVENT_ERROR;
 		break;
 	}