add special implementation for add

The special implementation does not need to allocate an array for the
varargs of addAll

primitiveCollections/src/test/java/org/lucares/collections/IntListTest.java

@@ -39,11 +39,9 @@ public class IntListTest {
 
 	@Test
 	public void testAdd() {
-		final IntList list = new IntList();
-
-		list.addAll();
-		Assert.assertTrue(list.isEmpty());
-		Assert.assertEquals(0, list.size());
+		// setting initial size to one, so that the first add does not need to resize,
+		// but the second add must
+		final IntList list = new IntList(1);
 
 		list.add(1);
 
@@ -179,6 +177,10 @@ public class IntListTest {
 	public void testAddArray() {
 		final IntList list = new IntList();
 
+		list.addAll();
+		Assert.assertTrue(list.isEmpty());
+		Assert.assertEquals(0, list.size());
+
 		final int size = 100;
 		final int[] ints = ThreadLocalRandom.current().ints(size).toArray();