backport patch for IceSSL

from:
https://github.com/sakuro/macports/blob/master/devel/zeroc-ice33/files/patch-ice.cpp.src.IceSSL.Instance.cpp.diff

should enable it to compile to completion on centos6/rhel6
Merge pull request #1 from stick/Ice-3.3.1

backport patch for IceSSL