STYLE: Use prefix increment in WeightedCovarianceSampleFilter.

Change-Id: I17461cadd51a25ef562301630e3d1b43bec386ed
BUG: MeasurementVectorSizeType in PointSetToListSampleAdaptor.

In the Statistics refactoring itk::Sample static consts MeasurementVectorSize
was removed in place of a runtime set m_MeasurementVectorSize.  However,
PointSetToListSampleAdaptor was not updated accordingly.

Change-Id: I1a0b11efe6eba854e1846d4661254024c8de322c
Merge topic 'above-array-bounds-warnings'

93657aa BUG: MeasurementVectorSizeType in PointSetToListSampleAdaptor.
0b504a0 STYLE: Use prefix increment in WeightedCovarianceSampleFilter.