Fix wxRmdir() with non-ASCII paths

Don't apply at best unnecessary, and actually harmful, as it uses a wrong
conversion, fn_str() when calling wxRmDir() which takes wxString.

Update unit tests to check that wxRmdir() now works with non-ASCII filenames
too.

Closes wxWidgets#17644.

docs/changes.txt

@@ -84,6 +84,7 @@ All:
   wxEvtHandler and/or wxTrackable in C++11 code (Raul Tambre, mmarsan).
 - Update bundled expat to 2.2.0 (Catalin Raceanu).
 - Add wxCMD_LINE_HIDDEN wxCmdLineParser flag (Lauri Nurmi).
+- Fix wxRmdir() with non-ASCII paths (trivia21).
 - Don't crash in wxFFile::Eof() or Error() on closed file (jprotopopov).
 
 All (GUI):

src/common/debugrpt.cpp

@@ -234,7 +234,7 @@ wxDebugReport::~wxDebugReport()
 
     if ( !m_dir.empty() )
     {
-        if ( wxRmDir(m_dir.fn_str()) != 0 )
+        if ( wxRmDir(m_dir) != 0 )
         {
             wxLogSysError(_("Failed to clean up debug report directory \"%s\""),
                           m_dir.c_str());

src/common/filefn.cpp

@@ -1192,7 +1192,7 @@ bool wxRmdir(const wxString& dir, int WXUNUSED(flags))
 #if defined(__VMS__)
     return false; //to be changed since rmdir exists in VMS7.x
 #else
-    if ( wxRmDir(dir.fn_str()) != 0 )
+    if ( wxRmDir(dir) != 0 )
     {
         wxLogSysError(_("Directory '%s' couldn't be deleted"), dir);
         return false;

tests/file/filefn.cpp

@@ -524,7 +524,7 @@ void FileFunctionsTestCase::PathOnly()
 // Rmdir fails on them on Linux. See ticket #17644.
 void FileFunctionsTestCase::Mkdir()
 {
-    wxString dirname = wxT("__wxMkdir_test_dir");
+    wxString dirname = wxString::FromUTF8("__wxMkdir_test_dir_with_\xc3\xb6");
     const std::string msg = wxString::Format("Dir: %s", dirname).ToStdString();
     CPPUNIT_ASSERT_MESSAGE( msg, wxMkdir(dirname) );
     CPPUNIT_ASSERT_MESSAGE( msg, wxDirExists(dirname) );
@@ -533,7 +533,7 @@ void FileFunctionsTestCase::Mkdir()
 
 void FileFunctionsTestCase::Rmdir()
 {
-    wxString dirname = wxT("__wxRmdir_test_dir");
+    wxString dirname = wxString::FromUTF8("__wxRmdir_test_dir_with_\xc3\xb6");
     const std::string msg = wxString::Format("Dir: %s", dirname).ToStdString();
 
     CPPUNIT_ASSERT_MESSAGE( msg, wxMkdir(dirname) );