Revert "AudioMixer: Remove tracks from enabledTracks after reseting outTemp"

This reverts commit 0debbf6b029f0967241f2c48f3136f5ae91102f7, it's apparently the cause of the recent audio buffering issues with YT across multiple platforms.

Change-Id: I917da7cafff58878918881c0fde9fb90c5096b39
libstagefright: fix AV sync late margin on non-QCOM_HARDWARE

Change I65cd3dce9b31b87f1488c37af9618669b29c362c changed the
late margin to a property defaulting to the same 40ms as the
original code, but uses QCOM_HARDWARE dependencies to read
the value (otherwise it's left unset).

Hardwire it back as the default 40ms

Change-Id: If63e171ea4e9693aa90dd7fabd8997f361a3959c
Merge remote-tracking branch 'PA/kitkat' into kitkat-legacy
Merge remote-tracking branch 'av/kitkat-legacy' into remix-legacy