Ensure that MSVC is new enough

Change-Id: I81c337e95e07f17f691c340ceaffdac55da78eb4
Reviewed-on: http://review.couchbase.org/34012
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>