Merge "Create libstagefright_mp3dec_headers" am: e9ebb9efbc am: e54bbcdfea

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/1525002

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I35ca6267d2f70e4d88175b846c55c252b07cc1a9