Fixing warning caused by local libosmocore version
diff --git a/lib/decoding/osmocom/core/bitvec.c b/lib/decoding/osmocom/core/bitvec.c
index 414c719..f877f21 100644
--- a/lib/decoding/osmocom/core/bitvec.c
+++ b/lib/decoding/osmocom/core/bitvec.c
@@ -36,6 +36,7 @@
  *
  * \file bitvec.c */
 
+#include <stdlib.h>
 #include <errno.h>
 #include <stdint.h>
 #include <string.h>