Make KClasses for primitives equal to KClasses for wrapper types

Both primitive int and wrapper type java.lang.Integer are represented by the
single type kotlin.Int in Kotlin, so inequality between the corresponding
KClasses was confusing here. To keep the old behavior, one may call 'k1.java ==
k2.java' instead of `k1 == k2`

 #KT-13462 Fixed

compiler/testData/codegen/box/reflection/classes/primitiveKClassEquality.kt

@@ -0,0 +1,15 @@
+// WITH_REFLECT
+
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+
+fun box(): String {
+    val x = Int::class.javaPrimitiveType!!.kotlin
+    val y = Int::class.javaObjectType.kotlin
+
+    assertEquals(x, y)
+    assertEquals(x.hashCode(), y.hashCode())
+    assertFalse(x === y)
+
+    return "OK"
+}

compiler/testData/codegen/box/reflection/supertypes/primitives.kt

@@ -11,10 +11,9 @@ fun box(): String {
     assertTrue(primitiveInt.isSubclassOf(primitiveInt))
     assertTrue(wrapperInt.isSubclassOf(wrapperInt))
 
-    // Currently KClass for int != KClass for java.lang.Integer, thus they are not a subclass of each other either
-    // TODO: reconsider this decision
-    assertFalse(primitiveInt.isSubclassOf(wrapperInt))
-    assertFalse(wrapperInt.isSubclassOf(primitiveInt))
+    // KClass for int equals KClass for java.lang.Integer, so they are also a subclass of each other
+    assertTrue(primitiveInt.isSubclassOf(wrapperInt))
+    assertTrue(wrapperInt.isSubclassOf(primitiveInt))
 
     return "OK"
 }