Initialize MD5 in logging in background

Use a background task to call MessageDigest.getInstance in order to
avoid a possible disk read on initialization.

Bug: 26069217
Change-Id: I0091ce012bcd811dfca0e85c21a12c54913ed919

telecomm/java/android/telecom/TelecomManager.java

@@ -498,6 +498,7 @@ public class TelecomManager {
             mContext = context;
         }
         mTelecomServiceOverride = telecomServiceImpl;
+        android.telecom.Log.initMd5Sum();
     }
 
     /**