AudioFlinger: Prevent offload underrun during active playback

Bug: 29897830
Change-Id: Id99d416cdaa8bf62daca8f92e3564f2895f15490
(cherry picked from commit f804475807407442d5596ab7378ed07d50664063)
(cherry picked from commit 39ee5a4f613b495d1582885f71f0d9d42411d68b)
2 files changed