Fix some missed size_t updates

Reviewed-by: Rich Salz <rsalz@openssl.org>

ssl/s3_msg.c

diff --git a/ssl/s3_msg.c b/ssl/s3_msg.c
index c016429..743a02b 100644
--- a/ssl/s3_msg.c
+++ b/ssl/s3_msg.c
@@ -15,7 +15,7 @@
     int i;
     size_t finish_md_len;
     const char *sender;
-    int slen;
+    size_t slen;
 
     if (s->server)
         i = SSL3_CHANGE_CIPHER_SERVER_READ;