fio: allow 0 as compress percentage

Allow 0 as value for option compress_percentage which can be useful for
certain deduplication and compression based storage back ends.

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/options.c b/options.c
index 04fb506..ac101a3 100644
--- a/options.c
+++ b/options.c
@@ -3069,7 +3069,7 @@
 		.type	= FIO_OPT_INT,
 		.off1	= td_var_offset(compress_percentage),
 		.maxval	= 100,
-		.minval	= 1,
+		.minval	= 0,
 		.help	= "How compressible the buffer is (approximately)",
 		.interval = 5,
 		.category = FIO_OPT_C_IO,