Fix forced-Lanscape mode for Fremantle PR1.2 (Maemo bug 10406)

PR1.2 broke forced-Landscape mode, as the window flags have
different semantics (although more sane) in the new version.

src/gpodder/gtkui/frmntl/portrait.py

@@ -161,7 +161,11 @@ def _orientation_changed(self, orientation):
             # Ignore repeated requests
             return
 
-        flags = hildon.PORTRAIT_MODE_SUPPORT
+        flags = 0
+
+        if orientation != self._LANDSCAPE:
+            flags |= hildon.PORTRAIT_MODE_SUPPORT
+
         if orientation == self._PORTRAIT:
             flags |= hildon.PORTRAIT_MODE_REQUEST