STYLE: Prefer returning int instead of bool in test method

Prefer returning `int` instead of `bool` in test method in order to
keep consistency in testing methods that return
`EXIT_SUCCESS`/`EXIT_FAILURE`.

Modules/Filtering/LabelMap/test/itkShapeLabelMapFilterGTest.cxx

@@ -98,7 +98,7 @@ class ShapeLabelMapFixture : public ::testing::Test
       return false;
     }
 
-    static bool
+    static int
     TestBasicObjectProperties()
     {
       using L2SType = itk::LabelImageToShapeLabelMapFilter<ImageType>;