Don't crash if XRC file contains '_' at the end of a string.

Parsing code for translating between '_' and '&' didn't properly handle
the case when the input was malformed and '_' wasn't followed by either
another '_' or another character. Added a check to guard against this.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70357 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

utils/wxrc/wxrc.cpp

@@ -896,7 +896,9 @@ static wxString ConvertText(const wxString& str)
     {
         if (*dt == wxT('_'))
         {
-            if ( *(++dt) == wxT('_') )
+            if ( *(dt+1) == 0 )
+                str2 << wxT('_');
+            else if ( *(++dt) == wxT('_') )
                 str2 << wxT('_');
             else
                 str2 << wxT('&') << *dt;