Share constants for droidstubs btw Soong & Bazel

Test: m bp2build && verify constants
Change-Id: I04865414fb627672821b10d8bcc736379dc3da86
diff --git a/java/config/Android.bp b/java/config/Android.bp
index 194e2c6..bfe83ab 100644
--- a/java/config/Android.bp
+++ b/java/config/Android.bp
@@ -12,6 +12,7 @@
     ],
     srcs: [
         "config.go",
+        "droidstubs.go",
         "error_prone.go",
         "kotlin.go",
         "makevars.go",