Allow trout targets to switch audio hal implementation Trout can run on both Cuttlefish and Emulator audio HAL implementations This CL allows switching those HALs by toggling a single build-time switch: TARGET_USES_CUTTLEFISH_AUDIO Bug: 166306608 Bug: 163092759 Test: build with cuttlefish audio, test that sound works Change-Id: I294b1787281aa85aab98b63f961da5f0410fd53c