freetdm: improved logic to enable/disable EC on call start/stop

- MFC-R2 requires tone signaling that gets screwed sometimes
           if the EC is enabled during call setup.
         - EC is now enabled only when switching to a state requiring
         media (UP and PROGRESS_MEDIA)
         - The logic is aware of EC persist option in Wanpipe
         - Improved logging in ftmod_wanpipe to print EC state on startup

libs/freetdm/src/include/private/ftdm_core.h

@@ -622,6 +622,9 @@ FT_DECLARE(ftdm_status_t) ftdm_span_trigger_signals(const ftdm_span_t *span);
 /*! \brief clear the tone detector state */
 FT_DECLARE(void) ftdm_channel_clear_detected_tones(ftdm_channel_t *ftdmchan);
 
+/* start/stop echo cancelling at the beginning/end of a call */
+FT_DECLARE(void) ftdm_set_echocancel_call_begin(ftdm_channel_t *chan);
+FT_DECLARE(void) ftdm_set_echocancel_call_end(ftdm_channel_t *chan);
 
 /*!
   \brief Assert condition
@@ -677,6 +680,14 @@ FT_DECLARE(void) ftdm_channel_clear_detected_tones(ftdm_channel_t *ftdmchan);
 #define ftdm_span_lock(span) ftdm_mutex_lock(span->mutex)
 #define ftdm_span_unlock(span) ftdm_mutex_unlock(span->mutex)
 
+#define ftdm_test_and_set_media(fchan) \
+		do { \
+			if (!ftdm_test_flag((fchan), FTDM_CHANNEL_MEDIA)) { \
+				ftdm_set_flag((fchan), FTDM_CHANNEL_MEDIA); \
+				ftdm_set_echocancel_call_begin((fchan)); \
+			} \
+		} while (0);
+
 FT_DECLARE_DATA extern const char *FTDM_LEVEL_NAMES[9];
 
 static __inline__ void ftdm_abort(void)

libs/freetdm/src/include/private/ftdm_types.h

@@ -227,16 +227,11 @@ typedef enum {
 #define FTDM_CHANNEL_OUTBOUND        (1ULL << 18)
 #define FTDM_CHANNEL_SUSPENDED       (1ULL << 19)
 #define FTDM_CHANNEL_3WAY            (1ULL << 20)
-
-/* this 3 flags are really nonsense used by boost module only, as soon
- * as we deprecate/delete boost module we can get rid of them 
- * ==================
- * */
 #define FTDM_CHANNEL_PROGRESS        (1ULL << 21)
+/*!< There is media on the channel already */
 #define FTDM_CHANNEL_MEDIA           (1ULL << 22)
+/*!< The channel was answered */
 #define FTDM_CHANNEL_ANSWERED        (1ULL << 23)
-/* ================== */
-
 #define FTDM_CHANNEL_MUTE            (1ULL << 24)
 #define FTDM_CHANNEL_USE_RX_GAIN     (1ULL << 25)
 #define FTDM_CHANNEL_USE_TX_GAIN     (1ULL << 26)