Fix comment in ssl_locl.h

The ciphers field in a session contains the stack of ciphers offered by
the client.
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6113)

ssl/ssl_locl.h

@@ -550,7 +550,7 @@ struct ssl_session_st {
     const SSL_CIPHER *cipher;
     unsigned long cipher_id;    /* when ASN.1 loaded, this needs to be used to
                                  * load the 'cipher' structure */
-    STACK_OF(SSL_CIPHER) *ciphers; /* shared ciphers? */
+    STACK_OF(SSL_CIPHER) *ciphers; /* ciphers offered by the client */
     CRYPTO_EX_DATA ex_data;     /* application specific data */
     /*
      * These are used to make removal of session-ids more efficient and to