Don't clear 'refill_buffers' unconditionally for pattern fill

If we have asked for a specific buffer compression, then we need
the refill option (if set).

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/options.c b/options.c
index 23469d8..c3c6292 100644
--- a/options.c
+++ b/options.c
@@ -1031,7 +1031,8 @@
 				&td->o.buffer_pattern_bytes);
 
 	if (!ret && td->o.buffer_pattern_bytes) {
-		td->o.refill_buffers = 0;
+		if (!td->o.compress_percentage)
+			td->o.refill_buffers = 0;
 		td->o.scramble_buffers = 0;
 		td->o.zero_buffers = 0;
 	} else {