Implement wxLocale::GetSystemEncodingName() for wxOSX.

Use CFStringGetNameOfEncoding() to get the canonical name of the encoding from
OS X itself.

Closes #2571.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72985 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/intl.cpp

@@ -781,8 +781,9 @@ wxString wxLocale::GetSystemEncodingName()
     UINT codepage = ::GetACP();
     encname.Printf(wxS("windows-%u"), codepage);
 #elif defined(__WXMAC__)
-    // default is just empty string, this resolves to the default system
-    // encoding later
+    encname = wxCFStringRef::AsString(
+                CFStringGetNameOfEncoding(CFStringGetSystemEncoding())
+              );
 #elif defined(__UNIX_LIKE__)
 
 #if defined(HAVE_LANGINFO_H) && defined(CODESET)