Branch and cache miss speedups

Just some low hanging fruit.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/filesetup.c b/filesetup.c
index 1acf6ad..2744d4f 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -1010,7 +1010,7 @@
 
 			seed = td->rand_seeds[FIO_RAND_BLOCK_OFF];
 			
-			if (!lfsr_init(&f->lfsr, blocks, seed, seed & 0xF))
+			if (!lfsr_init(&f->lfsr, blocks, seed, 0))
 				continue;
 		} else if (!td->o.norandommap) {
 			f->io_axmap = axmap_new(blocks);