Don't generate events from wxMSW wxSpinCtrl::SetValue(wxString)

The function was documented to not generate the events, but actually
did generate wxEVT_TEXT ones, even if it didn't generate wxEVT_SPINCTRL.

This was inconsistent with wxGTK and generic wxSpinCtrlDouble used under
MSW, so change this to avoid the unwanted events.

tests/controls/spinctrldbltest.cpp

@@ -177,9 +177,15 @@ TEST_CASE_METHOD(SpinCtrlDoubleTestCase,
     CHECK( m_spin->GetTextValue() == "57.30" );
     CHECK( m_spin->GetValue() == 57.3 );
 
+    CHECK( updatedSpin.GetCount() == 0 );
+    CHECK( updatedText.GetCount() == 0 );
+
     m_spin->SetValue("");
     CHECK( m_spin->GetTextValue() == "" );
     CHECK( m_spin->GetValue() == 0 );
+
+    CHECK( updatedSpin.GetCount() == 0 );
+    CHECK( updatedText.GetCount() == 0 );
 }
 
 #if wxUSE_UIACTIONSIMULATOR