dedupe_percentage should work even if compress_percentage is not set

Currently dedupe_percentage option does not work properly if
compress_percentage is not set. This can be easily demonstrated using
the following job file:

[job-/dev/dm-0]
filename=/dev/dm-0
rw=randwrite
blocksize=4096
direct=1
ioengine=libaio
iodepth=32
dedupe_percentage=50
time_based=1
runtime=5
numjobs=1

All writes will contain zeroes for the above job file.

The problem is in fill_io_buffer() function that switches dedupe random
state only if o->compress_percentage is set.

This patch updates the condition appropriately in fill_io_buffer()
appropriately.

Signed-off-by: Vasily Tarasov <tarasov@vasily.name>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/io_u.c b/io_u.c
index 77a3abf..f61fee8 100644
--- a/io_u.c
+++ b/io_u.c
@@ -1869,7 +1869,7 @@
 {
 	struct thread_options *o = &td->o;
 
-	if (o->compress_percentage) {
+	if (o->compress_percentage || o->dedupe_percentage) {
 		unsigned int perc = td->o.compress_percentage;
 		struct frand_state *rs;
 		unsigned int left = max_bs;