Fix handling of positional parameters in wxPrintf() and related.

Handle positional parameter specifications in wxFormatConverter to ensure that
e.g. "%N$s" are correctly transformed to "%N$S" if needed. This fixes the use
of positional parameters under OS X.

Closes #10965.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70523 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/strings/strings.cpp

@@ -165,6 +165,13 @@ void StringTestCase::Format()
         wxString s(wxT('Z'), len);
         CPPUNIT_ASSERT_EQUAL( len, wxString::Format(wxT("%s"), s.c_str()).length());
     }
+
+
+    CPPUNIT_ASSERT_EQUAL
+    (
+        "two one",
+        wxString::Format(wxT("%2$s %1$s"), wxT("one"), wxT("two"))
+    );
 }
 
 void StringTestCase::Constructors()