Kotlin/Native support

* Using Gradle 4.7
* Using Kotlin/Native 0.9-dev-2922

Fixes #246
diff --git a/settings.gradle b/settings.gradle
index 39eed4e..daa35af 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -3,6 +3,7 @@
  */
 
 rootProject.name = 'kotlinx.coroutines'
+enableFeaturePreview('GRADLE_METADATA')
 
 def module(String path) {
     int i = path.lastIndexOf('/')
@@ -43,5 +44,4 @@
 module('js/js-stub')
 module('js/example-frontend-js')
 
-//module('native/kotlinx-coroutines-core-native')
-
+module('native/kotlinx-coroutines-core-native')