add "behind" screen orientation to prevent spurious flipping

Calling setRequestedOrientation() before setContentView() used to
start activities off in the desired orientation even if the device
was in the opposite orientation, but now, there's a kind of lag
where they display briefly in the device orientation before
flipping to the request one. This change eliminates this effect.

bug: 4581374
Change-Id: I807b0a0a8a247ec8e51b85707afcbd9f75ed9956

AndroidManifest.xml

@@ -138,6 +138,7 @@
         <activity android:name=".wifi.WifiSettingsForSetupWizardXL"
                   android:theme="@android:style/Theme.Holo.NoActionBar"
                   android:windowBackground="@drawable/setups_bg_default"
+                  android:screenOrientation="behind"
                   android:clearTaskOnLaunch="true"
                   android:windowSoftInputMode="adjustResize"
                   android:exported="true" />