stagefright: Support for offloading MPEG2 audio

Change-Id: I8e76e9f98139c8f5170ee2bcc39682e5cba9dfa8
Fix M3UParser relative path handling.

Bug: 16017037
Change-Id: Ibfff99387fb5b3e721144a2b3f9174092d785137
M3UParser: check for NULL before setting meta data

Bug:16351654
Change-Id: I64e9510f719b220471522b4d78a9b00a98bda772
Fix Externally reported security issue

bug: 12724697
Change-Id: I57f37dbb3b01c0c3d3256be67c395352dd6ada13