Give audio GID to MANAGE_VOICE_KEYPHRASES apps.

Some system apps doing hotword training need low-level access to
audio hardware, beyond what the existing HAL offers.  For now, give
them the audio GID.

Bug: 17763721
Change-Id: I8025c3abacae13a6ffec4e10e4976a67ab505bdf
diff --git a/data/etc/platform.xml b/data/etc/platform.xml
index 91f5896..d3869b8 100644
--- a/data/etc/platform.xml
+++ b/data/etc/platform.xml
@@ -113,6 +113,12 @@
         <group gid="loop_radio" />
     </permission>
 
+    <!-- Hotword training apps sometimes need a GID to talk with low-level
+         hardware; give them audio for now until full HAL support is added. -->
+    <permission name="android.permission.MANAGE_VOICE_KEYPHRASES">
+        <group gid="audio" />
+    </permission>
+
     <!-- ================================================================== -->
     <!-- ================================================================== -->
     <!-- ================================================================== -->