Build leanback with Gradle.

Change-Id: Id3a2664149aa18b865957dca6aa8d44e3c062e62
diff --git a/v4/build.gradle b/v4/build.gradle
index 52f5b6e..59790bd 100644
--- a/v4/build.gradle
+++ b/v4/build.gradle
@@ -1,6 +1,11 @@
 apply plugin: 'android-library'
 archivesBaseName = 'support-v4'
 
+// create a jar task for the code internal implementation
+tasks.create(name: "internalJar", type: Jar) {
+    baseName "internal_impl"
+}
+
 // --------------------------
 // TO ADD NEW PLATFORM SPECIFIC CODE, UPDATE THIS:
 // create and configure the sourcesets/dependencies for platform-specific code.
@@ -36,6 +41,9 @@
         setupDependencies(configName, previousSource)
     }
     ext.allSS.add(sourceSet)
+
+    internalJar.from sourceSet.output
+
     return sourceSet
 }
 
@@ -44,15 +52,6 @@
     project.getDependencies().add(configName, previousSourceSet.compileClasspath)
 }
 
-// create a jar task for the code above
-tasks.create(name: "internalJar", type: Jar) {
-    baseName "internal_impl"
-}
-
-ext.allSS.each { ss ->
-    internalJar.from ss.output
-}
-
 dependencies {
     compile project(':support-annotations')