don't use fall back if we had already found the MIME type (patch 769826)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@22045 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/mimecmn.cpp

@@ -537,7 +537,7 @@ wxMimeTypesManager::GetFileTypeFromMimeType(const wxString& mimeType)
     EnsureImpl();
     wxFileType *ft = m_impl->GetFileTypeFromMimeType(mimeType);
 
-    if ( ft ) {
+    if ( !ft ) {
         // check the fallbacks
         //
         // TODO linear search is potentially slow, perhaps we should use a sorted