Add r8 alias for main:r8WithRelocatedDeps

Bug: 306064564
Change-Id: Icd84f4587977ce7a92069abe80a8c8a21a37c995
Fixes: 305969779
diff --git a/d8_r8/build.gradle.kts b/d8_r8/build.gradle.kts
index 704cb23..850a0c5 100644
--- a/d8_r8/build.gradle.kts
+++ b/d8_r8/build.gradle.kts
@@ -15,4 +15,8 @@
     dependsOn(gradle.includedBuild("library_desugar").task(":clean"))
     dependsOn(gradle.includedBuild("test").task(":clean"))
   }
+
+  val r8 by registering() {
+    dependsOn(gradle.includedBuild("main").task(":r8WithRelocatedDeps"))
+  }
 }