gtest: Don't use EQ/NE on iterators

This fails on VC9, see
https://groups.google.com/forum/#!msg/googletestframework/TI4wPTamEFE/-Wyu5esv0v8J

Change-Id: I1f7e098fd35f839926b4a741a069a62cbd5ef48e
Reviewed-on: http://review.couchbase.org/33351
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>