Fix grammatical error

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/backend.c b/backend.c
index efb17b3..e567ad5 100644
--- a/backend.c
+++ b/backend.c
@@ -1493,7 +1493,8 @@
 		}
 
 		if (left) {
-			log_err("fio: %d jobs failed to start\n", left);
+			log_err("fio: %d job%s failed to start\n", left,
+					left > 1 ? "s" : "");
 			for (i = 0; i < this_jobs; i++) {
 				td = map[i];
 				if (!td)