fix compilation error with gcc 7.2.0
diff --git a/src/cn-get.c b/src/cn-get.c
index cc276a5..79d3d72 100644
--- a/src/cn-get.c
+++ b/src/cn-get.c
@@ -13,6 +13,7 @@
       if (cp->v.uint == (unsigned long)key) {
         return cp->next;
       }
+      break;
     case CN_CBOR_INT:
       if (cp->v.sint == (long)key) {
         return cp->next;