pos can never be less than 0 as it's of type size_t

Also fix the type which is passed in from various places.

src/log.c

@@ -199,7 +199,7 @@ send_stored_logs(void)
 
 	int level;
 
-	int i;
+	size_t i;
 
 	for (i = 0; i != vector_length(log_message_storage); ++i) {
 		string = vector_getentry(log_message_storage, i, NULL);

src/reqs.c

@@ -117,7 +117,7 @@ add_connect_port_allowed(int port)
 static int
 check_allowed_connect_ports(int port)
 {
-	ssize_t i;
+	size_t i;
 	int *data;
 
 	/*

src/vector.c

@@ -180,7 +180,7 @@ vector_getentry(vector_t vector, size_t pos, size_t* size)
 	struct vectorentry_s *ptr;
 	size_t loc;
 
-	if (!vector || pos < 0 || pos >= vector->num_entries)
+	if (!vector || pos >= vector->num_entries)
 		return NULL;
 
 	loc = 0;