Do not consider 'expect' class type constructors final

Because even a final expected class can be actualized with an open
actual class and thus have subtypes in the platform code

compiler/testData/diagnostics/tests/multiplatform/headerClass/implOpenClass.kt

@@ -6,6 +6,8 @@ expect class Foo
 
 expect fun getFoo(): Foo
 
+fun <T : Foo> bar() {} // no "Foo is final" warning should be here
+
 // MODULE: m2-jvm(m1-common)
 // FILE: jvm.kt
 

compiler/testData/diagnostics/tests/multiplatform/headerClass/implOpenClass.txt

@@ -1,6 +1,7 @@
 // -- Module: <m1-common> --
 package
 
+public fun </*0*/ T : Foo> bar(): kotlin.Unit
 public expect fun getFoo(): Foo
 
 public final expect class Foo {
@@ -13,6 +14,7 @@ public final expect class Foo {
 // -- Module: <m2-jvm> --
 package
 
+public fun </*0*/ T : Foo> bar(): kotlin.Unit
 public actual fun getFoo(): Foo
 
 public final class Bar : Foo {

compiler/testData/diagnostics/tests/multiplatform/headerClass/smartCastOnExpectClass.kt

@@ -0,0 +1,13 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo { // also, it's important that Foo doesn't override equals
+    fun foo()
+}
+
+fun check(x1: Foo, x: Any) {
+    if (x1 == x) {
+        x.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+}

compiler/testData/diagnostics/tests/multiplatform/headerClass/smartCastOnExpectClass.txt

@@ -0,0 +1,10 @@
+package
+
+public fun check(/*0*/ x1: Foo, /*1*/ x: kotlin.Any): kotlin.Unit
+
+public final expect class Foo {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final expect fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}