Fix bug in wxStringOutputStream unit test.

We wrote an extra NUL byte to the stream and, unsurprisingly, contents of its
buffer didn't match the original string resulting in the test failure.

Also get rid of a #if wxUSE_UNICODE.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63249 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/streams/sstream.cpp

@@ -106,14 +106,8 @@ void strStream::CheckString(const wxString& text)
 {
     wxStringOutputStream sos;
 
-    size_t len = text.length();
-#if wxUSE_UNICODE
-    const wxCharBuffer textMB(wxConvLibc.cWC2MB(text.wc_str(), len + 1, &len));
-#else
-    const char *textMB = text.c_str();
-#endif
-
-    sos.Write(textMB, len);
+    const wxScopedCharBuffer buf(text.mb_str());
+    sos.Write(buf, buf.length());
 
     CPPUNIT_ASSERT_EQUAL( text, sos.GetString() );
 }