Suppress a harmless signed/unsigned comparison warning.

wxComboBox::FindString() used int loop index, change it to unsigned one.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63876 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/combobox_osx.cpp

@@ -172,7 +172,7 @@ int wxComboBox::FindString(const wxString& s, bool bCase) const
 {
     if (!bCase)
     {
-        for (int i = 0; i < GetCount(); i++)
+        for (unsigned i = 0; i < GetCount(); i++)
         {
             if (s.IsSameAs(GetString(i), false))
                 return i;