openssl-nativesdk: Fix "can't open config file" warning

openssl-nativesdk: Fix "can't open config file" warning

When SDK is not installed in the default location, openssl will not be
able to find the the openssl.cnf config file:

"WARNING: can't open config file: XXXX/usr/lib/ssl/openssl.cnf"

To fix this, we need to provide the environment variable $OPENSSL_CONF
pointing to the correct config file location.

Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>