Sketch Estimators: Fix merge function causing wrong results
Sketch Estimators: Fix merge function causing wrong results

Jira: MADLIB-567

The issue was in the merge function when the size of the input was large enough that
we switch from exact calculations to sketch based estimators.  The merge function was
failing to correctly account for the internal structure of the sketch data and OR-ing
the wrong byteas.

mktal/incubator-madlib,rvs/incubator-madlib,lmatthieu/incubator-madlib,mktal/incubator-madlib,cooper-sloan/incubator-madlib,madlib/madlib,iyerr3/incubator-madlib,njayaram2/madlib,mktal/incubator-madlib,lmatthieu/incubator-madlib,iyerr3/incubator-madlib,njayaram2/madlib,rvs/incubator-madlib,orhankislal/incubator-madlib,njayaram2/madlib,rashmi815/incubator-madlib,rashmi815/incubator-madlib,mktal/incubator-madlib,apache/incubator-madlib,madlib/madlib,iyerr3/incubator-madlib,apache/incubator-madlib,hpandeycodeit/incubator-madlib,orhankislal/madlib,cooper-sloan/incubator-madlib,orhankislal/incubator-madlib,orhankislal/incubator-madlib,iyerr3/incubator-madlib,apache/incubator-madlib,njayaram2/incubator-madlib,rashmi815/incubator-madlib,lmatthieu/incubator-madlib,rvs/incubator-madlib,orhankislal/madlib,cooper-sloan/incubator-madlib,cooper-sloan/incubator-madlib,njayaram2/incubator-madlib,lmatthieu/incubator-madlib,rvs/incubator-madlib,orhankislal/incubator-madlib,lmatthieu/incubator-madlib,hpandeycodeit/incubator-madlib,njayaram2/incubator-madlib,iyerr3/incubator-madlib,orhankislal/madlib,mktal/incubator-madlib,orhankislal/madlib,orhankislal/incubator-madlib,madlib/madlib,njayaram2/incubator-madlib,rashmi815/incubator-madlib,hpandeycodeit/incubator-madlib,madlib/madlib,rvs/incubator-madlib,orhankislal/madlib,apache/incubator-madlib,hpandeycodeit/incubator-madlib,apache/incubator-madlib,hpandeycodeit/incubator-madlib,njayaram2/incubator-madlib,rashmi815/incubator-madlib,madlib/madlib,njayaram2/madlib,njayaram2/madlib,cooper-sloan/incubator-madlib