message: Work around intel overload issues
  Intel is unable to distinguish between 'Attribute *' and 'IndexType'
  when passing AXOM_NULLPTR to overloaded functions.
diff: @@ -46,6 +46,9 @@ const double size_small = 1.2;
  const double size_medium = 2.3;
  const double size_large = 3.4;
  +// intel has a problem overloading 'Attribute *' and 'IndexType'.
  +Attribute * attr_null = AXOM_NULLPTR;
  +
  // Test protocols
  int nprotocols = 3;
  std::string const protocols[] = { "sidre_json", "sidre_hdf5", "json" };
  @@ -176,7 +179,7 @@ TEST(sidre_attribute,view_attr)
  View * view1a = grp1->createView(namea);
  EXPECT_TRUE( view1a != AXOM_NULLPTR );
  - EXPECT_FALSE(view1a->hasAttributeValue(AXOM_NULLPTR));
  + EXPECT_FALSE(view1a->hasAttributeValue(attr_null));
  EXPECT_FALSE(view1a->hasAttributeValue(attr_color));
  // Check values of unset attributes
  @@ -348,7 +351,7 @@ TEST(sidre_attribute,view_int_and_double)
  EXPECT_EQ(AXOM_NULLPTR, nostr);
  int i = -1;
  - i = view1a->getAttributeScalar(AXOM_NULLPTR);
  + i = view1a->getAttributeScalar(attr_null);
  EXPECT_EQ(0, i);
  delete ds;
  @@ -407,7 +410,7 @@ TEST(sidre_attribute,set_default)
  EXPECT_FALSE(view1a->hasAttributeValue(attr_size));
  // Check errors
  - ok = view1a->setAttributeToDefault(AXOM_NULLPTR);
  + ok = view1a->setAttributeToDefault(attr_null);
  EXPECT_FALSE( ok );
  delete ds;
  @@ -445,7 +448,7 @@ TEST(sidre_attribute,as_node)
  const Node & node2 = view1a->getAttributeNodeRef(attr_dump);
  EXPECT_EQ(dump_no, node2.as_int32());
  - const Node & node3 = view1a->getAttributeNodeRef(AXOM_NULLPTR);
  + const Node & node3 = view1a->getAttributeNodeRef(attr_null);
  EXPECT_TRUE(node3.schema().dtype().is_empty());
  delete ds;
  @@ -535,7 +538,7 @@ TEST(sidre_attribute,overloads)
  EXPECT_FALSE(view->hasAttributeValue(name_dump));
  // Check some errors
  - EXPECT_EQ(0, view->getAttributeScalar<int>(AXOM_NULLPTR));
  + EXPECT_EQ(0, view->getAttributeScalar<int>(attr_null));
  EXPECT_EQ(0, view->getAttributeScalar<int>(InvalidIndex));
  EXPECT_EQ(0, view->getAttributeScalar<int>("noname"));
  