support for extra class annotations

[aalleexxeeii]

When other class annotations (such as @serialversionuid) are required, the macro can't work: "Annotation is only supported on case class"

[jxnu-liguobin]

We can use match resolve it, like this:

      val (className, fields) = classDecl match {
        case q"$mods class $className(..$fields) extends ..$bases { ..$body }" =>
          if (!mods.asInstanceOf[Modifiers].hasFlag(Flag.CASE)) {
            c.abort(c.enclosingPosition, s"Annotation is only supported on case class. classDef: $classDecl, mods: $mods")
          } else {
            (className, fields)
          }
        case _ => c.abort(c.enclosingPosition, s"Annotation is only supported on case class. classDef: $classDecl")
      }