Add prebuilts/r8 to the bp2build BUILD file overwriting exception list.

Change-Id: I241d5e9a1bf1269a033d1f7c58e851610105c7fa
Test: b build prebuilts/r8:r8_jar_import
Bug: 194103854
diff --git a/android/bazel.go b/android/bazel.go
index 75b13c9..8f183ef 100644
--- a/android/bazel.go
+++ b/android/bazel.go
@@ -151,6 +151,7 @@
 
 		"prebuilts/sdk":/* recursive = */ false,
 		"prebuilts/sdk/tools":/* recursive = */ false,
+		"prebuilts/r8":/* recursive = */ false,
 		"packages/apps/Music":/* recursive = */ false,
 	}