avoid a warning by declaring struct gprs_ra_id opaquely
diff --git a/include/osmocom/ranap/ranap_common.h b/include/osmocom/ranap/ranap_common.h
index 459afe7..66b8c3e 100644
--- a/include/osmocom/ranap/ranap_common.h
+++ b/include/osmocom/ranap/ranap_common.h
@@ -591,6 +591,7 @@
 #include <osmocom/core/utils.h>
 #include <osmocom/ranap/ranap_ies_defs.h>
 
+struct gprs_ra_id;
 
 #define RANAP_DEBUG(x, args ...) DEBUGP(_ranap_DRANAP, x, ## args)
 extern int _ranap_DRANAP;