BUG: Initialize itk::Array local variable in doOneDimensionErode

Initialize `itk::Array` local `LineBuf` variable in
`itk::LabSet::doOneDimensionErode` function.

Fixes:
```
UMC ==954603== Conditional jump or move depends on uninitialised value(s)
==954603==    at 0x1B6A0A: void itk::LabSet::doOneDimensionErode >, itk::ImageLinearConstIteratorWithIndex >, itk::ImageLinearIteratorWithIndex >, itk::ImageLinearIteratorWithIndex >, float>(itk::ImageLinearConstIteratorWithIndex >&, itk::ImageLinearConstIteratorWithIndex >&, itk::ImageLinearIteratorWithIndex >&, itk::ImageLinearIteratorWithIndex >&, itk::ProgressReporter&, unsigned int, unsigned int, int, bool, float, float, float, float, bool) (itkLabelSetUtils.h:578)
==954603==    by 0x1B4251: itk::LabelSetErodeImageFilter, itk::Image >::ThreadedGenerateData(itk::ImageRegion<2u> const&, unsigned int) (itkLabelSetErodeImageFilter.hxx:128)
==954603==    by 0x18FE30: itk::ImageSource >::ThreaderCallback(void*) (itkImageSource.hxx:284)
==954603==    by 0x535686A: itk::PoolMultiThreader::SingleMethodExecute()::{lambda()#1}::operator()() const (itkPoolMultiThreader.cxx:142)
==954603==    by 0x5357F8B: void itk::(anonymous namespace)::ExceptionHandler::TryAndCatch(itk::PoolMultiThreader::SingleMethodExecute()::{lambda()#1} const&) (itkPoolMultiThreader.cxx:54)
==954603==    by 0x5356C4B: itk::PoolMultiThreader::SingleMethodExecute() (itkPoolMultiThreader.cxx:142)
==954603==    by 0x1B3BD8: itk::LabelSetMorphBaseImageFilter, false, itk::Image >::GenerateData() (itkLabelSetMorphBaseImageFilter.hxx:212)
==954603==    by 0x52D5FBF: itk::ProcessObject::UpdateOutputData(itk::DataObject*) (itkProcessObject.cxx:1692)
==954603==    by 0x52FDD8A: itk::DataObject::UpdateOutputData() (itkDataObject.cxx:384)
==954603==    by 0x166795: itk::ImageBase<2u>::UpdateOutputData() (itkImageBase.hxx:258)
==954603==    by 0x160EC5: itk::ImageFileWriter >::Write() (itkImageFileWriter.hxx:284)
==954603==    by 0x15C860: itk::ImageFileWriter >::Update() (itkImageFileWriter.h:180)
==954603==    by 0x1B0566: int doErode(char*, char*, int) (itkLabelSetErodeTest.cxx:58)
==954603==    by 0x1B014D: itkLabelSetErodeTest(int, char**) (itkLabelSetErodeTest.cxx:95)
==954603==    by 0x156227: main (LabelErodeDilateTestDriver.cxx:198)
```

raised for example in:
https://open.cdash.org/viewDynamicAnalysisFile.php?id=11279794

Author: jhlegarreta

include/itkLabelSetUtils.h

@@ -476,7 +476,7 @@ doOneDimensionErode(TInIter &          inputIterator,
     iscale = imageScale;
   }
   const RealType  magnitude = (magnitudeSign * iscale * iscale) / (2.0 * sigma);
-  LineBufferType  lineBuf(lineLength);
+  LineBufferType  lineBuf(lineLength, 0.0);
   LabelBufferType labBuf(lineLength);
 
   inputIterator.SetDirection(direction);