stagefright: move several static methods out of ACodec

Bug: 24761407
Change-Id: Ica1d0286b1e800f5d4d0f120c043c0a556dab4c2
Merged-In: Ica1d0286b1e800f5d4d0f120c043c0a556dab4c2
(cherry picked from commit 1ad5b240bfd49aa918092dbdc18c1a24c5e6c3a4)
4 files changed