Avoid Ycheck errors

Ycheck will check that each class member has a corresponding tree
in the template. We thus don't enter `clinit` as a member as we
cannot update the template.

Author: liufengyun

compiler/src/dotty/tools/backend/jvm/BCodeSkelBuilder.scala

@@ -128,7 +128,7 @@ trait BCodeSkelBuilder extends BCodeHelpers {
             MethodType(Nil)(_ => Nil, _ => defn.UnitType),
             privateWithin = NoSymbol,
             coord = claszSymbol.coord
-          ).entered
+          )
 
         val moduleField = ctx.newSymbol(
             claszSymbol,