added wxMBConv argument to char_str()

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@45496 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/string.h

@@ -1094,7 +1094,8 @@ public:
     // conversion to *non-const* multibyte or widestring buffer; modifying
     // returned buffer won't affect the string, these methods are only useful
     // for passing values to const-incorrect functions
-    wxWritableCharBuffer char_str() const { return mb_str(); }
+    wxWritableCharBuffer char_str(const wxMBConv& conv = wxConvLibc) const
+        { return mb_str(conv); }
     wxWritableWCharBuffer wchar_str() const { return wc_str(); }
 
     // conversion to/from plain (i.e. 7 bit) ASCII: this is useful for