->getevents() should take unsigned args

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/engines/posixaio.c b/engines/posixaio.c
index 9ff05c4..65a88e9 100644
--- a/engines/posixaio.c
+++ b/engines/posixaio.c
@@ -76,8 +76,8 @@
 	return 0;
 }
 
-static int fio_posixaio_getevents(struct thread_data *td, int min, int max,
-				  struct timespec *t)
+static int fio_posixaio_getevents(struct thread_data *td, unsigned int min,
+				  unsigned int max, struct timespec *t)
 {
 	struct posixaio_data *pd = td->io_ops->data;
 	struct list_head *entry;