Don't add $ROOT/cmake to include paths

This doesn't contain any actual header files!

Change-Id: I7f1e2b813a24bc950553f32607907c9cea2327ce
Reviewed-on: http://review.couchbase.org/42774
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>