Windows: Restrict the Service IOCTLS to the service process

When the service starts the system we save it's PID and when we see a
IOCTL_AFS_INITIALIZE_REDIRECTOR_DEVICE,
IOCTL_AFS_PROCESS_IRP_REQUEST, IOCTL_AFS_PROCESS_IRP_RESULT,
IOCTL_AFS_SYSNAME_NOTIFICATION or IOCTL_AFS_SYSNAME_NOTIFICATION
ioctl we check that the calling process has that PID.

Change-Id: Ie66676bba4b4e4d858979babe9c0af4c53ea0143
Reviewed-on: http://gerrit.openafs.org/8844
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>