enable disabling Linux perf usage through PCM_NO_PERF env variable
enable disabling Linux perf usage through PCM_NO_PERF env variable

export PCM_NO_PERF=1
no recompilation needed to disable Linux perf usage

Change-Id: I72c1e030e11820d06a9fec0f3966d6ffa98f9320

opcm/pcm,opcm/pcm,opcm/pcm,opcm/pcm