sysmobts: Add the necessary data structure and init for the SAPI queue

The sysmobts is now having a SAPI queue with all pending SAPI operations
on the BTS. Add the llist_head to the lchan and make sure it is initialized
by the shared code.

openbsc/include/openbsc/gsm_data_shared.h

@@ -246,6 +246,7 @@ struct gsm_lchan {
 #else
 	/* Number of different GsmL1_Sapi_t used in osmo_bts_sysmo is 23.
 	 * Currently we don't share these headers so this is a magic number. */
+	struct llist_head sapi_cmds;
 	uint8_t sapis_dl[23];
 	uint8_t sapis_ul[23];
 	struct lapdm_channel lapdm_ch;

openbsc/src/libcommon/gsm_data_shared.c

@@ -173,6 +173,10 @@ struct gsm_bts_trx *gsm_bts_trx_alloc(struct gsm_bts *bts)
 			lchan->ts = ts;
 			lchan->nr = l;
 			lchan->type = GSM_LCHAN_NONE;
+
+#ifndef ROLE_BSC
+			INIT_LLIST_HEAD(&lchan->sapi_cmds);
+#endif
 		}
 	}