don't assert on unsupported metric in wxSystemSettingsNative::GetMetric()

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56860 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/dfb/settings.cpp

@@ -78,7 +78,6 @@ int wxSystemSettingsNative::GetMetric(wxSystemMetric index,
             return val;
 
         default:
-            wxFAIL_MSG( "unsupported metric" );
             return -1;
     }
 }