[Generator] Do not use explicit final modifier in Native primitive classes

'final' is the default modality, safe to omit

generators/builtins/primitives/NativePrimitivesGenerator.kt

@@ -16,10 +16,6 @@ class NativePrimitivesGenerator(writer: PrintWriter) : BasePrimitivesGenerator(w
         import("kotlin.native.internal.*")
     }
 
-    override fun ClassBuilder.modifyGeneratedClass(thisKind: PrimitiveType) {
-        this.isFinal = true
-    }
-
     override fun CompanionObjectBuilder.modifyGeneratedCompanionObject(thisKind: PrimitiveType) {
         if (thisKind !in PrimitiveType.floatingPoint) {
             annotations += "CanBePrecreated"

generators/builtins/primitives/builders.kt

@@ -133,7 +133,6 @@ internal class FileBuilder(private val builtBy: String) : PrimitiveBuilder {
 }
 
 internal class ClassBuilder : AnnotatedAndDocumented(), PrimitiveBuilder {
-    var isFinal: Boolean = false
     var name: String = ""
     private var primaryConstructor: PrimaryConstructorBuilder = PrimaryConstructorBuilder()
     private var secondaryConstructor: SecondaryConstructorBuilder? = null
@@ -175,7 +174,6 @@ internal class ClassBuilder : AnnotatedAndDocumented(), PrimitiveBuilder {
             this.printDocumentationAndAnnotations()
 
             append("public ")
-            if (isFinal) append("final ")
             appendLine("class $name ${primaryConstructor.build()}: ${superTypes.joinToString()} {")
 
             secondaryConstructor?.let {