audio HAL: add output flag indicating support for gapless transitions

Add output profile flag AUDIO_OUTPUT_FLAG_GAPLESS_OFFLOAD to be used in
conjunction with AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD to indicate
that gapless transitions are supported when playing compressed audio.

Bug: 158191844
Test: make
Change-Id: Ifa551ff36d8571062cac3ad38f89be2f3addb960
diff --git a/audio/7.0/config/api/current.txt b/audio/7.0/config/api/current.txt
index 1da8b09..0b2e4a4 100644
--- a/audio/7.0/config/api/current.txt
+++ b/audio/7.0/config/api/current.txt
@@ -259,6 +259,7 @@
     enum_constant public static final android.audio.policy.configuration.V7_0.AudioInOutFlag AUDIO_OUTPUT_FLAG_DIRECT;
     enum_constant public static final android.audio.policy.configuration.V7_0.AudioInOutFlag AUDIO_OUTPUT_FLAG_DIRECT_PCM;
     enum_constant public static final android.audio.policy.configuration.V7_0.AudioInOutFlag AUDIO_OUTPUT_FLAG_FAST;
+    enum_constant public static final android.audio.policy.configuration.V7_0.AudioInOutFlag AUDIO_OUTPUT_FLAG_GAPLESS_OFFLOAD;
     enum_constant public static final android.audio.policy.configuration.V7_0.AudioInOutFlag AUDIO_OUTPUT_FLAG_HW_AV_SYNC;
     enum_constant public static final android.audio.policy.configuration.V7_0.AudioInOutFlag AUDIO_OUTPUT_FLAG_IEC958_NONAUDIO;
     enum_constant public static final android.audio.policy.configuration.V7_0.AudioInOutFlag AUDIO_OUTPUT_FLAG_INCALL_MUSIC;