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

compiler/testData/codegen/light-analysis/enum/kt9711.txt

@@ -1,7 +1,9 @@
+@kotlin.Metadata
 public final class Kt9711Kt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }
 
+@kotlin.Metadata
 public abstract enum class X {
     public final static field B: X
     inner class X/B
@@ -11,6 +13,7 @@ public abstract enum class X {
     public static method values(): X[]
 }
 
+@kotlin.Metadata
 final static class X/B {
     private final @org.jetbrains.annotations.NotNull field value2: java.lang.String
     private final @org.jetbrains.annotations.NotNull field value: kotlin.jvm.functions.Function0