Fixed build warning on OS X due to macro redefinition.
Fixed build warning on OS X due to macro redefinition.

Change-Id: I38d0847a2342e0032f4efc330563dbeb9b852d52
Reviewed-on: http://review.couchbase.org/c/libcouchbase/+/155246
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>

couchbase/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase