Add buffer_compress_percentage

The option is pending testing, so not documented yet.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index 5c912d0..7443bc0 100644
--- a/fio.h
+++ b/fio.h
@@ -194,6 +194,7 @@
 	unsigned int zero_buffers;
 	unsigned int refill_buffers;
 	unsigned int scramble_buffers;
+	unsigned int compress_percentage;
 	unsigned int time_based;
 	unsigned int disable_lat;
 	unsigned int disable_clat;