Disable JIT, fix rendering issues on Mediatek 4.2 devices

See https://github.com/cgeo/cgeo/issues/4097 for discussion

AndroidManifest.xml

@@ -29,7 +29,8 @@
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
 
     <application android:label="@string/app_name" android:icon="@drawable/icon"
-	    android:theme="@style/DefaultTheme" >
+	    android:theme="@style/DefaultTheme"
+	    android:vmSafeMode="true">
 
         <activity android:name=".APRSdroid"
 		android:configChanges="orientation|keyboardHidden|screenSize"