Use wxScopedCharBuffer in To8BitData() in ANSI build too.

This allows one to write code compatible with both Unicode and ANSI
builds.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64789 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/string.h

@@ -492,12 +492,7 @@ public:
 
         @see wxString::From8BitData()
     */
-    const char* To8BitData() const;
-
-    /**
-        @overload
-    */
-    const wxCharBuffer To8BitData() const;
+    const wxScopedCharBuffer To8BitData() const;
 
     /**
         Converts the string to an ASCII, 7-bit string in the form of