Interleave buffers while sending to writer

Test: ./amrnb_writer_fuzzer
Test: ./amrwb_writer_fuzzer
Test: ./mpeg4_writer_fuzzer
Test: ./ogg_writer_fuzzer
Test: ./webm_writer_fuzzer
Bug: 173672210
Bug: 173672657
Bug: 173672212
Bug: 173672344

Change-Id: I5a08507459e4072f599468dc2f618b3b0175a961