Native: allow jsinterop and cinterop (legacy sourcecode mode) using SymbolName

The interop Kotlin source generators still use `@SymbolName` to link
Kotlin code with platform code.

kotlin-native/utilities/cli-runner/src/main/kotlin/org/jetbrains/kotlin/cli/utilities/InteropCompiler.kt

@@ -61,6 +61,7 @@ fun invokeInterop(flavor: String, args: Array<String>): Array<String>? {
         "-o", outputFileName,
         "-target", target.visibleName,
         "-manifest", manifest.path,
+        "-opt-in=kotlin.native.SymbolNameIsInternal",
         "-Xtemporary-files-dir=$temporaryFilesDir") +
         nativeStubs +
         cinteropArgsToCompiler +