[mod_spandsp] Fix compilation against >=2023/06/02 spandsp

spandsp, beginning with commit d9681c37 and coinciding with the
SPANDSP_RELEASE_DATE of 20230620, introduced the following changes to
its V.18 protocol API, which FreeSWITCH is not able to compile against:
- Certain V.18 constants were renamed.
- The v18_init function now requires passing a third function, handling
the V.18 modem's status changes.

This patch allows FreeSWITCH to build against current versions of
spandsp by:
- Using the new V.18 constant names.
- Implementing a simple status reporter callback function and passing it
as the third function to v18_init.

Additionally, it retains backward compatibility with prior versions of
spandp through #if conditions checking the value of
SPANDSP_RELEASE_DATE.

Signed-off-by: Patrice Fournier <patrice.fournier@t38fax.com>

src/mod/applications/mod_spandsp/mod_spandsp.c

@@ -37,7 +37,6 @@
 
 
 #include "mod_spandsp.h"
-#include <spandsp/version.h>
 #include "mod_spandsp_modem.h"
 
 /* **************************************************************************

src/mod/applications/mod_spandsp/mod_spandsp.h

@@ -58,6 +58,12 @@ typedef int zap_socket_t;
 #define SPANDSP_EVENT_TXFAXNEGOCIATERESULT "spandsp::txfaxnegociateresult"
 #define SPANDSP_EVENT_RXFAXNEGOCIATERESULT "spandsp::rxfaxnegociateresult"
 
+#include <spandsp/version.h>
+
+#if SPANDSP_RELEASE_DATE < 20230620
+#define V18_MODE_WEITBRECHT_5BIT_4545 V18_MODE_5BIT_4545
+#define V18_MODE_WEITBRECHT_5BIT_50   V18_MODE_5BIT_50
+#endif
 
 
 /* The global stuff */

src/mod/applications/mod_spandsp/mod_spandsp_dsp.c

@@ -152,17 +152,28 @@ static void put_text_msg(void *user_data, const uint8_t *msg, int len)
 
 }
 
+#if SPANDSP_RELEASE_DATE >= 20230620
+static void handle_v18_status(void *user_data, int status)
+{
+	switch_tdd_t *pvt = (switch_tdd_t *) user_data;
+	switch_channel_t *channel = switch_core_session_get_channel(pvt->session);
+
+	switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(pvt->session), SWITCH_LOG_INFO, "%s detected V.18 modem: %s\n", switch_channel_get_name(channel), v18_status_to_str(status));
+
+}
+#endif
+
 static int get_v18_mode(switch_core_session_t *session)
 {
 	switch_channel_t *channel = switch_core_session_get_channel(session);
 	const char *var;
-	int r = V18_MODE_5BIT_4545;
+	int r = V18_MODE_WEITBRECHT_5BIT_4545;
 
 	if ((var = switch_channel_get_variable(channel, "v18_mode"))) {
 		if (!strcasecmp(var, "5BIT_45") || !strcasecmp(var, "baudot")) {
-			r = V18_MODE_5BIT_4545;
+			r = V18_MODE_WEITBRECHT_5BIT_4545;
 		} else if (!strcasecmp(var, "5BIT_50")) {
-			r = V18_MODE_5BIT_50;
+			r = V18_MODE_WEITBRECHT_5BIT_50;
 		} else if (!strcasecmp(var, "DTMF")) {
 			r = V18_MODE_DTMF;
 		} else if (!strcasecmp(var, "EDT")) {
@@ -213,8 +224,11 @@ switch_status_t spandsp_tdd_send_session(switch_core_session_t *session, const c
 		return SWITCH_STATUS_FALSE;
 	}
 
+#if SPANDSP_RELEASE_DATE >= 20230620
+	tdd_state = v18_init(NULL, TRUE, get_v18_mode(session), V18_AUTOMODING_GLOBAL, put_text_msg, NULL, handle_v18_status, NULL);
+#else
 	tdd_state = v18_init(NULL, TRUE, get_v18_mode(session), V18_AUTOMODING_GLOBAL, put_text_msg, NULL);
-
+#endif
 
 	v18_put(tdd_state, text, -1);
 
@@ -260,7 +274,13 @@ switch_status_t spandsp_tdd_encode_session(switch_core_session_t *session, const
 	}
 
 	pvt->session = session;
+
+#if SPANDSP_RELEASE_DATE >= 20230620
+	pvt->tdd_state = v18_init(NULL, TRUE, get_v18_mode(session), V18_AUTOMODING_GLOBAL, put_text_msg, NULL, handle_v18_status, pvt);
+#else
 	pvt->tdd_state = v18_init(NULL, TRUE, get_v18_mode(session), V18_AUTOMODING_GLOBAL, put_text_msg, NULL);
+#endif
+
 	pvt->head_lead = TDD_LEAD;
 
 	v18_put(pvt->tdd_state, text, -1);
@@ -338,7 +358,12 @@ switch_status_t spandsp_tdd_decode_session(switch_core_session_t *session)
 	}
 
 	pvt->session = session;
+
+#if SPANDSP_RELEASE_DATE >= 20230620
+	pvt->tdd_state = v18_init(NULL, FALSE, get_v18_mode(session), V18_AUTOMODING_GLOBAL, put_text_msg, pvt, handle_v18_status, pvt);
+#else
 	pvt->tdd_state = v18_init(NULL, FALSE, get_v18_mode(session), V18_AUTOMODING_GLOBAL, put_text_msg, pvt);
+#endif
 
 	if ((status = switch_core_media_bug_add(session, "spandsp_tdd_decode", NULL,
 						tdd_decode_callback, pvt, 0, SMBF_READ_REPLACE | SMBF_NO_PAUSE, &bug)) != SWITCH_STATUS_SUCCESS) {