fix libmix encoder klockwork issues, rename IntelMetadatabuffer APIs

BZ: 50695

fix libmix encoder klockwork issues, remove all unused variables;
rename IntelMetadatabuffer APIs, rename SetBytes to UnSerialize,
GetBytes to Serialize, SetBytes/GetBytes will be dropped later;
Refine encoder code to avoid dynamic memory allocation.
Resubmit patch due to last patch's wrong BZ number issue

Change-Id: Ib072e40aed440c6c9eb641992d631bb7e5f83483
Signed-off-by: Zhao Liang <>
Reviewed-by: Ding, Haitao <>
Tested-by: Ding, Haitao <>
Reviewed-by: buildbot <>
Tested-by: buildbot <>
8 files changed