Revert "WIN32 MemoryTracking: track wcsdup() _wcsdup() and _tcsdup() usage"

This reverts commit 8ec2cb5544.

We don't have any code anywhere in libcurl (or the curl tool) that use
wcsdup so there's no such memory use to track. It seems to cause mild
problems with the Borland compiler though that we may avoid by reverting
this change again.

Bug: http://curl.haxx.se/mail/lib-2013-05/0070.html

lib/curl_setup.h

@@ -270,7 +270,6 @@
 #    endif
 #  endif
 #  include <tchar.h>
-   typedef wchar_t *(*curl_wcsdup_callback)(const wchar_t *str);
 #endif
 
 /*