Windows: Fix cm_AppendServerList

Should use || and not | as the operator when testing for
NULL pointers.

Reviewed-on: http://gerrit.openafs.org/11523
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit ba0b0986ecd6407fc07d5733ca741c1e5fa7bf52)

Change-Id: I02134a4bded6a38a14548b8117230d161093f2c9
Reviewed-on: http://gerrit.openafs.org/11614
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>