Apparently it is possible to have chm file without #STRINGS in it, so we should not stop processing file at it. Fixes bug #12498

[Juan Lang]

Hi Tomasz,

-        info->WinType.pszToc = strdupW(info->pCHMInfo->defToc);
+        info->WinType.pszToc = strdupW(info->pCHMInfo->defToc ?
info->pCHMInfo->defToc : null);

Please don't use null, it's not portable.  Also, what has this change
accomplished?  If strdupW succeeds when passed NULL, the existing line
would already have done the same thing, so you've added a test for no
benefit.
--Juan