Telephony: Support muting by RIL command

While almost everyone already moved to AudioManager years ago,
some OEMs (cough Huawei) still use RIL for muting and don't
promote the necessary calls in their audio HAL.
Let's handle these odd cases too when it's necessary.

Change-Id: Id916dec2574d6e57b6f809fbaf2b0959c0cc7256

src/com/android/services/telephony/TelephonyConnection.java

@@ -25,6 +25,7 @@
 import android.os.Looper;
 import android.os.Message;
 import android.os.PersistableBundle;
+import android.os.SystemProperties;
 import android.telecom.CallAudioState;
 import android.telecom.ConferenceParticipant;
 import android.telecom.Connection;
@@ -697,6 +698,10 @@ public void onCallAudioStateChanged(CallAudioState audioState) {
         // TODO: update TTY mode.
         if (getPhone() != null) {
             getPhone().setEchoSuppressionEnabled();
+
+	if (SystemProperties.getBoolean("persist.sys.radio.huawei", false)) {
+                getPhone().setMute(audioState.isMuted());
+            }
         }
     }