FS-9765 one tweak from submitted patch to use switch_channel_var_true instead of…

FS-9765 one tweak from submitted patch to use switch_channel_var_true instead of switch_channel_get_variable no need to allocate on every hold/unhold just to check if this is enabled.

src/mod/endpoints/mod_sofia/sofia.c

@@ -7602,10 +7602,13 @@ static void sofia_handle_sip_i_state(switch_core_session_t *session, int status,
 				goto done;
 			}
 
-
-			switch_core_media_gen_local_sdp(session, SDP_TYPE_RESPONSE, NULL, 0, NULL,
+			if (switch_channel_var_true(channel, "sip_unhold_nosdp")) {
+				switch_core_media_gen_local_sdp(session, SDP_TYPE_RESPONSE, NULL, 0, "sendrecv",
+												zstr(tech_pvt->mparams.local_sdp_str) || !switch_channel_test_flag(channel, CF_PROXY_MODE));
+			} else {
+				switch_core_media_gen_local_sdp(session, SDP_TYPE_RESPONSE, NULL, 0, NULL,
 											zstr(tech_pvt->mparams.local_sdp_str) || !switch_channel_test_flag(channel, CF_PROXY_MODE));
-
+			}
 
 			if (zstr(tech_pvt->mparams.local_sdp_str)) {
 				switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_WARNING, "Cannot find a SDP\n");