Fixed a few invalid conversions found by UBSan
- Switched from int to vtkIdType to make overflow less likely for this: Common/DataModel/vtkPointLocator.h:282:31: runtime error: value -1.5748e+299 is outside the range of representable values of type 'int'
Really GetBucketIndices() should change from int to vtkIdType too, but that's more invasive.
- Reduced while loop iterations to fix negative double to unsigned int conversion: /Rendering/FreeType/vtkFreeTypeTools.cxx:2362:30: runtime error: value -23.5789 is outside the range of representable values of type 'unsigned int'