hal_audio: Allow writing dump info into pipes when capturing BR

The following HAL methods use file descriptors to write dump
info comprising audioflinger debug dump:

IDevice.debugDump
IEffectsFactory.debugDump
IStream.debugDump

Bug: 37993476
Test: check contents of media.audio_flinger section in
      a bugreport captured on Pixel device

Change-Id: I77d347c019ac93c3ba0d54ce50f0fdc243b04685