[MONDRIAN-2049] compound slicer members were not factored in aggStar selection for Children

fixes NPE with agg enabled in
 NativeSetEvaluationTest.testConstraintCacheIncludesMultiPositionSlicer
 BasicQueryTest.testCompoundSlicerNonEmpty
Merge pull request #38 from tgf/evergreen

[MONDRIAN-2049] compound slicer members were not factored in aggStar sel...