Audio: Add memory leak checking for HAL

$ adb shell setprop libc.debug.malloc.program android.hardware.audio.service
$ adb shell setprop libc.debug.malloc.options backtrace=8
$ adb shell setenforce 0
$ adb shell pkill audioserver
$ adb shell dumpsys media.audio_flinger

Test: Check the audio flinger dumpsys as above.
Bug: 186054996
Bug: 187462632
Change-Id: I2e8db14b816cc4cd7e1420c538505bf71fa58c97