Add r8lib task alias

Change-Id: I9908895b7f5052f50bedd7ec06d774f08dc444b8
diff --git a/d8_r8/build.gradle.kts b/d8_r8/build.gradle.kts
index 850a0c5..187f708 100644
--- a/d8_r8/build.gradle.kts
+++ b/d8_r8/build.gradle.kts
@@ -19,4 +19,8 @@
   val r8 by registering() {
     dependsOn(gradle.includedBuild("main").task(":r8WithRelocatedDeps"))
   }
+
+  val r8lib by registering() {
+    dependsOn(gradle.includedBuild("test").task(":assembleR8LibWithRelocatedDeps"))
+  }
 }