Prevent empty output when input is single-point mesh.

Revert previous change.

Correct striding issue when numPts = 1. Loop was correct when comparing
with MaximumNumberOfPoints-1, but should have been adjusted when localMaxPts
was introduced.

Change-Id: Iad15ade5619f2c83891cc550739e12eafeb248b9
Merge topic 'mask_points_can_yield_empty_output' into master

36b6a31f Prevent empty output when input is single-point mesh.