[Native] Move addFile from IrUtils2

This function is actually used only in `BackendPhases` and it is
too specific to be included into utils.

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/BackendPhases.kt

@@ -19,12 +19,15 @@ import org.jetbrains.kotlin.backend.konan.makeEntryPoint
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.backend.konan.objcexport.createTestBundle
+import org.jetbrains.kotlin.descriptors.impl.PackageFragmentDescriptorImpl
+import org.jetbrains.kotlin.ir.IrFileEntry
 import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
+import org.jetbrains.kotlin.ir.declarations.impl.IrFileImpl
 import org.jetbrains.kotlin.ir.util.NaiveSourceBasedFileEntryImpl
 import org.jetbrains.kotlin.ir.util.addChild
-import org.jetbrains.kotlin.ir.util.addFile
 import org.jetbrains.kotlin.ir.util.file
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.resolve.scopes.MemberScope
 
 internal data class SpecialBackendChecksInput(
         val irModule: IrModuleFragment,
@@ -99,3 +102,11 @@ internal val CreateTestBundlePhase = createSimpleNamedCompilerPhase<PhaseContext
     val output = OutputFiles(config.outputPath, config.target, config.produce).mainFile
     createTestBundle(config, input.moduleDescriptor, output)
 }
+
+private fun IrModuleFragment.addFile(fileEntry: IrFileEntry, packageFqName: FqName): IrFile {
+    val packageFragmentDescriptor = object : PackageFragmentDescriptorImpl(this.descriptor, packageFqName) {
+        override fun getMemberScope(): MemberScope = MemberScope.Empty
+    }
+
+    return IrFileImpl(fileEntry, packageFragmentDescriptor).also { this.files += it }
+}

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/ir/util/IrUtils2.kt

@@ -59,15 +59,6 @@ internal fun IrFile.addTopLevelInitializer(expression: IrExpression, context: Ko
     addChild(irField)
 }
 
-fun IrModuleFragment.addFile(fileEntry: IrFileEntry, packageFqName: FqName): IrFile {
-    val packageFragmentDescriptor = object : PackageFragmentDescriptorImpl(this.descriptor, packageFqName) {
-        override fun getMemberScope(): MemberScope = MemberScope.Empty
-    }
-
-    return IrFileImpl(fileEntry, packageFragmentDescriptor)
-            .also { this.files += it }
-}
-
 fun IrBuilderWithScope.irCatch() =
         IrCatchImpl(
                 startOffset, endOffset,