build: fix some warnings

Fix a couple of warnings:

-Werror=unused-parameter

so we can use meson's warning_level=3 and -Werror without build
failures.

Change-Id: I14487a56727469f6bda1cabccce8241ac1acb149
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/test/utest.cpp b/test/utest.cpp
index 5fb870f..8e0091e 100644
--- a/test/utest.cpp
+++ b/test/utest.cpp
@@ -53,8 +53,7 @@
     }
 
     // Callback handler on data
-    static int callbackHandler(sd_event_source* es, int fd, uint32_t revents,
-                               void* userData)
+    static int callbackHandler(sd_event_source*, int, uint32_t, void*)
     {
         std::cout << "Event fired" << std::endl;
         completed = true;