Fix SSL certificate CNAME checking

Currently, accessing a host via ip address will pass SSL verification;
the CNAME is not checked as intended as part of verify_callback.

'preverify_ok is True' will always return false (int/bool comparison).
preverify_ok will be 1 if preverification has passed.

Fixes bug 1192229

Change-Id: Ib651548ab4289295a9b92ee039b2aff2d08aba5f
(cherry picked from commit 822cd64c0718b46a065abbb8709f6b466d12e708)