[LSC] Add LOCAL_LICENSE_KINDS to external/Reactive-Extensions/RxCpp am: 6e6c469a7c am: c17d041feb am: 234f2f2fda am: 5f4c3264fe am: 5b2db4c7ce

Original change: https://android-review.googlesource.com/c/platform/external/Reactive-Extensions/RxCpp/+/1588615

Change-Id: I816c4f71ab4914a36b9c0ac5785cd163b355c637