Deprecate use of some audio effects on output mix.

The possibility for applications to apply insert audio effects
(Equalizer, BassBoost, Virtualizer) on global output mix has brought up
a number of issue.

This change updates the java doc for audio effects indicating that
application should not apply insert effects globaly anymore as this behavior
will soon be deprecated.

The audio framework will still allow global insert effects during an interim
period but will give the priority to effects inserted on particular player by
disabling global effects when both are present.

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Change-Id: If87f1944a0409d45d8d2eee66ff331f95965ca89