OpenSSL: don't disable security work-around

OpenSSL added a work-around for a SSL 3.0/TLS 1.0 CBC vulnerability
(http://www.openssl.org/~bodo/tls-cbc.txt). In 0.9.6e they added a bit
to SSL_OP_ALL that _disables_ that work-around despite the fact that
SSL_OP_ALL is documented to do "rather harmless" workarounds.

The libcurl code uses the SSL_OP_ALL define and thus logically always
disables the OpenSSL fix.

In order to keep the secure work-around workding, the
SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS bit must not be set and this change
makes sure of this.

Reported by: product-security at Apple