add osmo_sockaddr_to_str_buf/osmo_sockaddr_to_str

Add helper to format osmo_sockaddr into a string.

Change-Id: I917f25ebd1239eae5855d973ced15b93731e33a0
diff --git a/include/osmocom/core/socket.h b/include/osmocom/core/socket.h
index 9878240..0443c06 100644
--- a/include/osmocom/core/socket.h
+++ b/include/osmocom/core/socket.h
@@ -118,5 +118,9 @@
 int osmo_sockaddr_cmp(const struct osmo_sockaddr *a,
 		      const struct osmo_sockaddr *b);
 
+const char *osmo_sockaddr_to_str(const struct osmo_sockaddr *sockaddr);
+char *osmo_sockaddr_to_str_buf(char *buf, size_t buf_len,
+			       const struct osmo_sockaddr *sockaddr);
+
 #endif /* (!EMBEDDED) */
 /*! @} */