Properly initialize md5 hash seed

We started from 0, that's not entirely correct.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/verify.c b/verify.c
index 5770b46..566c53c 100644
--- a/verify.c
+++ b/verify.c
@@ -187,7 +187,7 @@
 		.hash = hash,
 	};
 
-	memset(md5_ctx.hash, 0, sizeof(hdr->md5_digest));
+	md5_init(&md5_ctx);
 	md5_update(&md5_ctx, p, hdr->len - sizeof(*hdr));
 
 	if (memcmp(hdr->md5_digest, md5_ctx.hash, sizeof(hash))) {
@@ -279,7 +279,7 @@
 		.hash = (uint32_t *) hdr->md5_digest,
 	};
 
-	memset(md5_ctx.hash, 0, sizeof(hdr->md5_digest));
+	md5_init(&md5_ctx);
 	md5_update(&md5_ctx, p, len);
 }