mod_ssl: return non ambiguous value in ssl_callback_SessionTicket() for

mod_ssl: return non ambiguous value in ssl_callback_SessionTicket() for
encryption mode (we used to return 0, OpenSSL documents returning 1 instead).

Practically this does not change anything since OpenSSL will only check for
>= 0 return value (non error) for encryption mode (the other possible return
values are only relevant for decryption mode).

However the OpenSSL documentation for SSL_CTX_set_tlsext_ticket_key_cb()
states:
"
The return value of the cb function is used by OpenSSL to determine what
further processing will occur. The following return values have meaning:

2
    This indicates that the ctx and hctx have been set and the session can
    continue on those parameters. Additionally it indicates that the session
    ticket is in a renewal period and should be replaced. The OpenSSL library
    will call cb again with an enc argument of 1 to set the new ticket (see
    RFC5077 3.3 paragraph 2).

1
    This indicates that the ctx and hctx have been set and the session can
    continue on those parameters.

0
    This indicates that it was not possible to set/retrieve a session ticket
    and the SSL/TLS session will continue by by negotiating a set of
    cryptographic parameters or using the alternate SSL/TLS resumption
    mechanism, session ids.
    If called with enc equal to 0 the library will call the cb again to get a
    new set of parameters.

less than 0
    This indicates an error.
"

So 0 is not appropriate in our code, 1 is what we really want (and it won't
break if OpenSSL later changes its checks on the callback return value).

Reported/Proposed by: oknet on github, pull request #18.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1736186 13f79535-47bb-0310-9956-ffa450edef68