csn1: add CSN_DESCR_EXTERN for extern declarations

Change-Id: Ieb721c97c8e9acee5057bb04be73f27b2871687b
---
M include/osmocom/csn1/csn1.h
1 file changed, 3 insertions(+), 0 deletions(-)

diff --git a/include/osmocom/csn1/csn1.h b/include/osmocom/csn1/csn1.h
index 0f58895..a87f5a0 100644
--- a/include/osmocom/csn1/csn1.h
+++ b/include/osmocom/csn1/csn1.h
@@ -225,6 +225,9 @@
 #define CSN_DESCR_END(_STRUCT) \
 	{CSN_END, 0, {0}, 0, FALSE, "", 0, NULL} };
 
+#define CSN_DESCR_EXTERN(_STRUCT) \
+	extern const CSN_DESCR CSNDESCR_##_STRUCT[]
+
 /******************************************************************************
  * CSN_ERROR(Par1, Par2, Par3)
  * May be called at any time when an abort of packing or unpacking of a message

