Fix IrFunction.isEmptyArray implementation

The previous one was incorrect for K1 since parent of top-level function
is `IrClass`, not `IrPackageFragment`.

The change is non-functional, K1 still worked correctly, but had to do
some extra work when inlining `emptyArray` calls and produces less
performant bytecode.

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/VarargLowering.kt

@@ -113,6 +113,4 @@ internal fun IrFunction.isArrayOf(): Boolean {
             valueParameters[0].isVararg
 }
 
-internal fun IrFunction.isEmptyArray(): Boolean =
-    name.asString() == "emptyArray" &&
-            (parent as? IrPackageFragment)?.packageFqName == StandardNames.BUILT_INS_PACKAGE_FQ_NAME
+internal fun IrFunction.isEmptyArray(): Boolean = isTopLevelInPackage("emptyArray", StandardNames.BUILT_INS_PACKAGE_FQ_NAME)