MPEG4Writer:Print longest 5 write durations

Using priority queue, maintain longest 5 write durations and print them
as debug logs during stop.

Bug: 159254170

Test: atest android.media.cts.MediaMuxerTest \
        android.mediav2.cts.MuxerTest \
        android.mediav2.cts.MuxerUnitTest \
        android.media.cts.MediaRecorderTest
Change-Id: I86fcbde66ec387d1aafb2bdbd6f9b2a72a17f977
Merged-In: I86fcbde66ec387d1aafb2bdbd6f9b2a72a17f977