Fix tests and db_dump compilation.

apps/db_dump/stubs.c

@@ -10,10 +10,8 @@
 #  define UNUSED(A) (void)(A)
 #endif
 
-struct mosquitto *context__init(mosq_sock_t sock)
+struct mosquitto *context__init(void)
 {
-	UNUSED(sock);
-
 	return NULL;
 }
 

test/unit/persist_read_stubs.c

@@ -14,12 +14,10 @@ extern int last_qos;
 extern uint32_t last_identifier;
 extern struct mosquitto_db db;
 
-struct mosquitto *context__init(mosq_sock_t sock)
+struct mosquitto *context__init(void)
 {
 	struct mosquitto *m;
 
-	UNUSED(sock);
-
 	m = mosquitto__calloc(1, sizeof(struct mosquitto));
 	if(m){
 		m->msgs_in.inflight_maximum = 20;

test/unit/persist_write_stubs.c

@@ -13,10 +13,8 @@ extern uint64_t last_retained;
 extern char *last_sub;
 extern int last_qos;
 
-struct mosquitto *context__init(mosq_sock_t sock)
+struct mosquitto *context__init(void)
 {
-	UNUSED(sock);
-
 	return mosquitto__calloc(1, sizeof(struct mosquitto));
 }