Use _CRT_SECURE_NO_WARNINGS on win32

Change-Id: I7f9828d282e8171ce8aea8d3318d2fa7886c2744
Reviewed-on: http://review.couchbase.org/27905
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>