Allow audioserver to talk to bluetooth server

Audioserver loads A2DP module directly. The A2DP module
talks to the bluetooth server.

Bug: 37640821
Test: Play Music over BT headset
Change-Id: Ie6233e52a3773b636a81234b73e5e64cfbff458e

private/audioserver.te

@@ -42,6 +42,9 @@ allow audioserver audio_data_file:file create_file_perms;
 # allow access to ALSA MMAP FDs for AAudio API
 allow audioserver audio_device:chr_file { read write };
 
+# For A2DP bridge which is loaded directly into audioserver
+unix_socket_connect(audioserver, bluetooth, bluetooth)
+
 ###
 ### neverallow rules
 ###