libstagefright: Re-introduce a QCOM_HARDWARE ifdef after the FFMPEG commit

Fixes a build error on non QCOM hardware.

Change-Id: I4a4268b351d0d8bf748dd03ccea0fbab20ed4314
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_frameworks_av into cm-11.0