client/server: zlib error code fixup

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/client.c b/client.c
index f7b050b..678a627 100644
--- a/client.c
+++ b/client.c
@@ -1000,7 +1000,8 @@
 		stream.avail_out = this_chunk;
 		stream.next_out = p;
 		err = inflate(&stream, Z_NO_FLUSH);
-		if (err != Z_OK) {
+		/* may be Z_OK, or Z_STREAM_END */
+		if (err < 0) {
 			log_err("fio: inflate error %d\n", err);
 			free(ret);
 			ret = NULL;