Remove extraneous ADDITIONAL_LIBS variable, which was used in an earlier attempt.
Remove extraneous ADDITIONAL_LIBS variable, which was used in an earlier attempt.

firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk