Configure: warn if using. CMake should be used instead

Change-Id: I2490e7db90502b574feaa776197ff66ca11879ee
Reviewed-on: http://review.couchbase.org/43533
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>