COMP: Address HasNumericTraits failure for Vector pixel type.

Use default initialization instead of initialization with 0, which
does not work for all numeric pixel type.

Author: blowekamp

Modules/Core/Common/include/itkConceptChecking.h

@@ -706,7 +706,7 @@ struct HasNumericTraits
       Detail::UniqueType<typename NumericTraits<T>::RealType>();
       Detail::UniqueType<typename NumericTraits<T>::ScalarRealType>();
       Detail::UniqueType<typename NumericTraits<T>::FloatType>();
-      T a{ 0 };
+      T a{};
 
       // Test these methods that take an instance of T to
       // allow for types with variable length.

Modules/Core/Common/test/itkNumericTraitsTest.cxx

@@ -1299,5 +1299,14 @@ itkNumericTraitsTest(int, char *[])
   // CompileTime Checks IsComplex traits does not return
   CheckIsComplexTraits();
 
+  itkConceptMacro(NumericTraitsCheckLong, (itk::Concept::HasNumericTraits<long>));
+  itkConceptMacro(NumericTraitsCheckComplexFloat, (itk::Concept::HasNumericTraits<std::complex<float>>));
+  itkConceptMacro(NumericTraitsCheckVectorFloat3, (itk::Concept::HasNumericTraits<itk::Vector<float, 3>>));
+  itkConceptMacro(NumericTraitsCheckStdVectorFloat, (itk::Concept::HasNumericTraits<std::vector<float>>));
+  itkConceptMacro(NumericTraitsCheckVariableLengthVector,
+                  (itk::Concept::HasNumericTraits<itk::VariableLengthVector<double>>));
+  itkConceptMacro(NumericTraitsCheckRGBPixel, (itk::Concept::HasNumericTraits<itk::RGBPixel<unsigned char>>));
+  itkConceptMacro(NumericTraitsCheckRGBAPixel, (itk::Concept::HasNumericTraits<itk::RGBAPixel<unsigned char>>));
+
   return (testPassedStatus) ? EXIT_SUCCESS : EXIT_FAILURE;
 }