[codecs filter] add trans.cc.codecs

Add the central codecs_filter for Call Control. The new member is not
used in this patch yet, subsequent patches will start to populate the
various stages of this codec filter, one by one.

Related: SYS#5066
Change-Id: Ib3fdeff8d1e1ea0760168d63ee6e1b1fb993aa5f
diff --git a/include/osmocom/msc/transaction.h b/include/osmocom/msc/transaction.h
index 14b89bb..0966627 100644
--- a/include/osmocom/msc/transaction.h
+++ b/include/osmocom/msc/transaction.h
@@ -8,6 +8,7 @@
 #include <osmocom/msc/mncc.h>
 #include <osmocom/msc/msc_a.h>
 #include <osmocom/msc/debug.h>
+#include <osmocom/msc/codec_filter.h>
 #include <osmocom/gsm/gsm0411_smc.h>
 #include <osmocom/gsm/gsm0411_smr.h>
 
@@ -101,6 +102,8 @@
 			struct gsm_mncc msg;	/* stores setup/disconnect/release message */
 			bool mncc_initiated;	/* Whether an MNCC Release is necessary on failure */
 			struct osmo_lcls *lcls;
+			/* Track codec choices from BSS and remote call leg */
+			struct codec_filter codecs;
 		} cc;
 		struct {
 			struct gsm411_smc_inst smc_inst;