Be more secure about pointers in event lists (win32 plugin)

Change-Id: I4be3ff3d833170df800af436cc981b28bc711053
Reviewed-on: http://review.couchbase.org/24477
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>