Update d8 task to visit zipped files

Bug: 211400706
Change-Id: I75f422ce704de2a482e456232d5aaa0632e61c24
diff --git a/build.gradle b/build.gradle
index bfd11a0..8be67ce 100644
--- a/build.gradle
+++ b/build.gradle
@@ -933,7 +933,7 @@
 
 task D8(type: Jar) {
     dependsOn r8
-    from r8.outputs.files[0]
+    from zipTree(r8.outputs.files[0])
     archiveFileName = 'd8.jar'
     manifest {
         attributes 'Main-Class': 'com.android.tools.r8.D8'