Update our MIME type map.

Bug: https://code.google.com/p/android/issues/detail?id=61996
Change-Id: I55efc9d38c87d89bb20073e4632ab1e06c77be09
Fix MimeUtils to treat ".flac" as "audio/flac".

(cherry-pick of 77926e913a14b9541df38b6175f795f2ca6c5266.)

Bug: 15715370
Change-Id: I2d99f070c3debea01621a172d8189951a56736b5