Remove fullscreen android:theme where it hides the menu

Many of the Android samples rely on an options menu to work properly
but, at least on newer devices, the menu is permanently hidden by the
Android theme "Theme.NoTitleBar.Fullscreen", which means that most
of the examples were dysfunctional.

samples/android/tutorial-2-mixedprocessing/AndroidManifest.xml

@@ -6,8 +6,7 @@
 
     <application
         android:label="@string/app_name"
-        android:icon="@drawable/icon"
-        android:theme="@android:style/Theme.NoTitleBar.Fullscreen" >
+        android:icon="@drawable/icon">
 
         <activity android:name="Tutorial2Activity"
                   android:label="@string/app_name"

samples/android/tutorial-2-mixedprocessing/gradle/AndroidManifest.xml

@@ -5,8 +5,7 @@
 
     <application
         android:label="@string/app_name"
-        android:icon="@drawable/icon"
-        android:theme="@android:style/Theme.NoTitleBar.Fullscreen" >
+        android:icon="@drawable/icon">
 
         <activity android:name="Tutorial2Activity"
                   android:label="@string/app_name"