Abort using SIGABRT instead of SIGKILL on command_timeout

This will produce a stack trace and flag for automated crash reporting.

Bug: 36026072
Test: net_test_bluetooth; device off/on/off tests
Change-Id: I4d4380d61028261ba7bb4599e39993cae1d906a5

system/hci/src/hci_layer.cc

@@ -409,7 +409,7 @@ static void command_timed_out(UNUSED_ATTR void* context) {
 
   LOG_ERROR(LOG_TAG, "%s restarting the bluetooth process.", __func__);
   usleep(10000);
-  kill(getpid(), SIGKILL);
+  abort();
 }
 
 // Event/packet receiving functions