Fix compiler warnings from Clang 10 and GCC 9.

[meshlink] / catta

diff --git a/catta b/catta
index 08ac450b42b7533e97c02c02bbbef8946b9582fb..bb173469810e4c7de19e53793d4af2e27e6e222c 160000 (submodule)
--- a/catta
+++ b/catta
@@ -1 +1 @@
-Subproject commit 08ac450b42b7533e97c02c02bbbef8946b9582fb
+Subproject commit bb173469810e4c7de19e53793d4af2e27e6e222c