Make fio -Wshadow clean

Found a few issues, actually.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/client.c b/client.c
index edc02a0..e9eab81 100644
--- a/client.c
+++ b/client.c
@@ -654,15 +654,13 @@
 
 	fd = open(filename, O_RDONLY);
 	if (fd < 0) {
-		int ret = -errno;
-
+		ret = -errno;
 		log_err("fio: job file <%s> open: %s\n", filename, strerror(errno));
 		return ret;
 	}
 
 	if (fstat(fd, &sb) < 0) {
-		int ret = -errno;
-
+		ret = -errno;
 		log_err("fio: job file stat: %s\n", strerror(errno));
 		close(fd);
 		return ret;