Speed up id3v2 unsynchronization

Instead of doing many overlapping memmoves, do a single copy pass
that skips over the inserted unsynchronization bytes. For some
files this reduces parsing time from minutes to milliseconds.

Similar to commit 72a43b68 but for v2.2 and v2.3.

Bug: 78029004
Test: poc
Change-Id: I735b7051e77a093d86fb7a3e46209875946225ed
(cherry picked from commit f9d87cc8)
CVE-2018-9412