FS-3599 --resolve correct windows compiler warnings

libs/freetdm/mod_freetdm/mod_freetdm.c

@@ -507,7 +507,7 @@ static switch_status_t channel_on_hangup(switch_core_session_t *session)
 	const char *name = NULL;
 	int span_id = 0;
 	int chan_id = 0;
-	int t = 0;
+	uint32_t t = 0;
 	uint32_t tokencnt;
 	char *uuid = NULL;
 	const char *token = NULL;

libs/freetdm/src/ftdm_io.c

@@ -3969,7 +3969,9 @@ FT_DECLARE(ftdm_status_t) ftdm_channel_process_media(ftdm_channel_t *ftdmchan, v
 				if (ftdmchan->state == FTDM_CHANNEL_STATE_CALLWAITING && (digit_char == 'D' || digit_char == 'A')) {
 					ftdmchan->detected_tones[FTDM_TONEMAP_CALLWAITING_ACK]++;
 				} else {
-					char digit_str[2] = { digit_char, 0};
+					char digit_str[2] = { 0 };
+
+					digit_str[0] = digit_char;
 					
 					if (!ftdmchan->span->sig_dtmf || (ftdmchan->span->sig_dtmf(ftdmchan, (const char*)digit_str) != FTDM_BREAK)) {
 						ftdm_channel_queue_dtmf(ftdmchan, digit_str);