Compilation fix after last commit.

wxApp::GetTraitsIfExists() doesn't exist in 2.8, mea culpa for backporting the
trunk fix without testing.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@63949 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/unix/mimetype.cpp

@@ -1527,7 +1527,8 @@ void wxMimeTypesManagerImpl::InitIfNeeded()
         m_initialized = true;
 
         int mailcapStyles = wxMAILCAP_ALL;
-        if ( wxAppTraits * const traits = wxApp::GetTraitsIfExists() )
+        if ( wxAppTraits * const traits = wxTheApp ? wxTheApp->GetTraits()
+                                                   : NULL )
         {
             wxString wm = traits->GetDesktopEnvironment();