Set default visibility to private

Takes advantage of a new mechanism for specifying the default visibility
of all modules in a package to restrict the visibility of wycheproof
modules as much as possible:
  package {default_visibility: ["//visibility:private"]}

Bug: 133290645
Bug: 134379140
Test: m droid
Change-Id: I8fdf009e5d4f38c0ca3e051efa1ef36a2ac948ff
diff --git a/Android.bp b/Android.bp
index 3a4142f..765c264 100644
--- a/Android.bp
+++ b/Android.bp
@@ -14,8 +14,16 @@
 // limitations under the License.
 //
 
+package {
+    default_visibility: ["//visibility:private"],
+}
+
 java_library_static {
     name: "wycheproof",
+    visibility: [
+        "//cts/tests/libcore/wycheproof",
+        "//cts/tests/libcore/wycheproof-bc",
+    ],
     srcs: ["java/**/*.java"],
     exclude_srcs: [
         "java/com/google/security/wycheproof/SpongyCastleTest.java",