Include builtin_audio_encoder_factory.h in peer_connection_dependency_factory.cc

Also add builtin_audio_encoder_factory to deps.
Also move the builtin_audio_decoder_factory into the deps that's added only if building with webrtc.

BUG=webrtc:5806

Review-Url: https://codereview.chromium.org/2808743004
Cr-Commit-Position: refs/heads/master@{#471747}
2 files changed