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

src/xrc/xmlres.cpp

@@ -1554,7 +1554,7 @@ wxString wxXmlResourceHandler::GetText(const wxString& param, bool translate)
         // like "&File..." -- this is illegal in XML, so we use "_File..."):
         if ( *dt == amp_char )
         {
-            if ( *(++dt) == amp_char )
+            if ( dt+1 == str1.end() || *(++dt) == amp_char )
                 str2 << amp_char;
             else
                 str2 << wxT('&') << *dt;

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;