Squashed QCOM DirectTrack commits

stagefright: Conditionally build legacy audio stuff

 * The LPA and Tunnel mode code is entirely deprecated and breaks things
   for devices which don't use the legacy ALSA audio HAL.
 * Exclude this stuff unless explicitly requested.
 * Also enable rendering statistics for all.

av: Additional ifdefs for QCOM DirectTrack

 * Tunnel and LPA mode on legacy QC devices requires the DirectTrack
   code path, which going forward has been deprecated.
 * In order to properly support QC features on 8974, this needs broken
   out in order to not cause problems on new devices.
 * With this patch, QCOM_HARDWARE will enable features common to all
   QC platforms (including legacy), and legacy support will
   automatically be enabled based on the use of driver variant and
   value of BOARD_USES_LEGACY_ALSA_AUDIO.

Revert "frameworks/av: rendering statistics for Stagefright."

This reverts commit 1a65f74eebe15e1533ebde98268a454a8b14f815.

Revert "libstagefright: adjust AV sync late margin based on property"

This reverts commit 14b0bb438a8b3291edd10fb068656e707a31cfb5.

Revert "libstagefright: post video events dynamically - calculate amount of time to delay video event after renderusing the formula: delay = (us between frames)-(us taken by event)-(lateness)"

This reverts commit 1ac2a4f83f7d14b3a4d9c4691a5d6bb62fcc5522.

Change-Id: I3a164d42915a74b3d9b0799f06ea9e8389440996