Fix all compiler warnings found using -Wall -W -pedantic.

[meshlink] / src / utcp

diff --git a/src/utcp b/src/utcp
index 850542e9585f716985c25d5995ba5bcb2cc6ba87..d0c4523ccd8998a70262fb11e015ea807d4aaba7 160000 (submodule)
--- a/src/utcp
+++ b/src/utcp
@@ -1 +1 @@
-Subproject commit 850542e9585f716985c25d5995ba5bcb2cc6ba87
+Subproject commit d0c4523ccd8998a70262fb11e015ea807d4aaba7