audioserver: allow audioserver to generate audio HAL tombstones

Allow audioserver to signal audio HAL processes and
generate tombstones in case of watchdog restart.

Bug: 141528385
Test: Force watchdog and verify tombstone creation
Change-Id: I39bb4a63aa93efab68baad3890b8f49fc5f79ead
diff --git a/public/audioserver.te b/public/audioserver.te
index 2ad86e3..a8a33cc 100644
--- a/public/audioserver.te
+++ b/public/audioserver.te
@@ -1,3 +1,6 @@
 # audioserver - audio services daemon
 type audioserver, domain;
 type audioserver_tmpfs, file_type;
+
+# Allow audioserver to signal audio HAL processes and dump their stacks.
+allow audioserver hal_audio_server:process signal;