Kapt3: Write stub class files with metadata (needed for incremental compilation)

compiler/testData/codegen/light-analysis/defaultArguments/function/funInTrait.txt

@@ -1,18 +1,22 @@
+@kotlin.Metadata
 public interface Foo {
     inner class Foo/DefaultImpls
     public abstract method foo(p0: double): double
 }
 
+@kotlin.Metadata
 public final class Foo/DefaultImpls {
     inner class Foo/DefaultImpls
     public synthetic static method foo$default(p0: Foo, p1: double, p2: int, p3: java.lang.Object): double
 }
 
+@kotlin.Metadata
 public final class FooImpl {
     public method <init>(): void
     public method foo(p0: double): double
 }
 
+@kotlin.Metadata
 public final class FunInTraitKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }