tests: Fix warnings

This fixes warnings that are raised by missing includes, missing casts,
missing return statements, using printf %lu with uint64_t, and unused
symbols.
diff --git a/tests/auth/milenage_test.c b/tests/auth/milenage_test.c
index 7c996f0..0223764 100644
--- a/tests/auth/milenage_test.c
+++ b/tests/auth/milenage_test.c
@@ -7,6 +7,8 @@
 #include <osmocom/crypt/auth.h>
 #include <osmocom/core/utils.h>
 
+int milenage_opc_gen(uint8_t *opc, const uint8_t *k, const uint8_t *op);
+
 static void dump_auth_vec(struct osmo_auth_vector *vec)
 {
 	printf("RAND:\t%s\n", osmo_hexdump(vec->rand, sizeof(vec->rand)));
@@ -88,7 +90,7 @@
 	if (rc < 0) {
 		printf("AUTS failed\n");
 	} else {
-		printf("AUTS success: SEQ.MS = %lu\n", test_aud.u.umts.sqn);
+		printf("AUTS success: SEQ.MS = %llu\n", (unsigned long long)test_aud.u.umts.sqn);
 	}
 
 	opc_test(&test_aud);