AudioEffect: fix racy access to callback data

Since the EffectCallback in android::AudioEffect can
keep an instance of the latter alive for a longer time
than Java AudioEffect is alive, the callback need to
ensure that it's not trying to use deallocated objects
and deleted JVM references.

Bug: 178363662
Test: manual using EffectsTest app
Test: atest CtsMediaTestCases:AudioEffectTest
Test: atest CtsMediaTestCases:BassBoostTest
Test: atest CtsMediaTestCases:DynamicsProcessingTest
Test: atest CtsMediaTestCases:EnvReverbTest
Test: atest CtsMediaTestCases:EqualizerTest
Test: atest CtsMediaTestCases:LoudnessEnhancerTest
Test: atest CtsMediaTestCases:PresetReverbTest
Test: atest CtsMediaTestCases:VisualizerTest
Change-Id: I8c36f5af4a1a2b14e81b1344570d2f8746ffa91e