Cleanup vendor projects are proprietary.

Test: m droid dist
Change-Id: I0bdec38c4d12710fa97b91665d211ba6c0d4b24d

libwvdrmengine/mediacrypto/Android.bp

@@ -19,6 +19,7 @@
 package {
     // See: http://go/android-license-faq
     //   legacy_by_exception_only (by exception only)
+    //   legacy_proprietary (by exception only)
     default_applicable_licenses: ["vendor_widevine_license"],
 }