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

compiler/testData/codegen/light-analysis/arrays/kt1291.txt

@@ -1,3 +1,4 @@
+@kotlin.Metadata
 public final class Kt1291Kt {
     private static field result: int
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
@@ -7,6 +8,7 @@ public final class Kt1291Kt {
     public final static method setResult(p0: int): void
 }
 
+@kotlin.Metadata
 public final class Selector {
     private final @org.jetbrains.annotations.NotNull field f: kotlin.jvm.functions.Function1
     private final @org.jetbrains.annotations.NotNull field source: java.util.Iterator