JVM IR: fail when SyntheticAccessorLowering adds accessor to other files

This would help for example in debugging the issue fixed in the previous
commit.

The only problem by now where this lowering tried to add accessors to
foreign files was reproduced for interfaces inheriting from Cloneable.
There, we generate a DefaultImpls bridge that calls protected method
`clone` from java.lang.Cloneable.DefaultImpls. This makes no sense, but
the old backend behaves the same. Instead of generating accessor for it
in JVM IR, we now see all DefaultImpls bridges as public as a
workaround. (The fact that assertion no longer fails here is checked
e.g. by box/reflection/mapping/methodsFromObject.kt.)

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt

@@ -11,9 +11,9 @@ import org.jetbrains.kotlin.backend.common.deepCopyWithVariables
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibilities
+import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.ir.IrElement
-import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.builders.Scope
 import org.jetbrains.kotlin.ir.declarations.*
@@ -514,6 +514,7 @@ fun createStaticFunctionWithReceivers(
     dispatchReceiverType: IrType? = oldFunction.dispatchReceiverParameter?.type,
     origin: IrDeclarationOrigin = oldFunction.origin,
     modality: Modality = Modality.FINAL,
+    visibility: Visibility = oldFunction.visibility,
     copyMetadata: Boolean = true
 ): IrSimpleFunction {
     val descriptor = (oldFunction.descriptor as? DescriptorWithContainerSource)?.let {
@@ -524,7 +525,7 @@ fun createStaticFunctionWithReceivers(
         origin,
         IrSimpleFunctionSymbolImpl(descriptor),
         name,
-        oldFunction.visibility,
+        visibility,
         modality,
         oldFunction.returnType,
         isInline = oldFunction.isInline,