Add wxFSW_EVENT_ATTRIB wxFileSystemWatcher flag.

This flag allows to monitor changes to the file attributes, such as file
modification time.

This patch adds the flag, support for it under Linux and the corresponding
modifications to the sample and the test suite.

Closes #14833.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72977 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/fswatcher/fswatcher.cpp

@@ -535,6 +535,8 @@ static wxString GetFSWEventChangeTypeName(int changeType)
         return "MODIFY";
     case wxFSW_EVENT_ACCESS:
         return "ACCESS";
+    case wxFSW_EVENT_ATTRIB: // Currently this is wxGTK-only
+        return "ATTRIBUTE";
     }
 
     return "INVALID_TYPE";