MB-8185: Add healthchecker module to build

Change-Id: Ie75e35e8bc380ce72cc85c5995499b77160646bc
Reviewed-on: http://review.couchbase.org/26048
Reviewed-by: Philip Labee <philip@couchbase.com>
Reviewed-by: Bin Cui <bin.cui@gmail.com>
Tested-by: Bin Cui <bin.cui@gmail.com>