Add visibity for androidx prebuilts.

Test: make
Change-Id: I9114ea285729d962366230d32f254619edd5ffa5
diff --git a/Android.bp b/Android.bp
index df1881f..e3b3fa4 100644
--- a/Android.bp
+++ b/Android.bp
@@ -22,5 +22,6 @@
     visibility: [
         "//external/dagger2",
         "//external/kotlinx.atomicfu",
+        "//prebuilts/sdk/current/androidx",
     ],
 }