Restrict visibility of intra.core.stubs

All accesses to intra.core.stubs are done by the
core-intra-stubs-system-modules so this makes intra.core.stubs private.

Test: m checkbuild
Change-Id: I77c916f8d285e42a5706bb1b7efb673813f94d88
diff --git a/mmodules/intracoreapi/Android.bp b/mmodules/intracoreapi/Android.bp
index 011015f..cb40d94 100644
--- a/mmodules/intracoreapi/Android.bp
+++ b/mmodules/intracoreapi/Android.bp
@@ -49,10 +49,6 @@
 // core jars.
 java_library {
     name: "core.intra.stubs",
-    visibility: [
-        "//external/conscrypt",
-        "//libcore",
-    ],
     srcs: [":core-intra-stubs"],
 
     sdk_version: "none",