Fix wxFileSystemWatcher::RemoveAll() to actually work.

We need to call DoRemove() on all watcher objects to really remove them, just
removing our record of them was not enough and e.g. resulted in errors if we
tried to re-add a previously watched path again.

Closes #15531.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76187 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/private/fswatcher.h

@@ -84,8 +84,16 @@ public:
 
     virtual bool RemoveAll()
     {
+        bool ret = true;
+        for ( wxFSWatchEntries::iterator it = m_watches.begin();
+              it != m_watches.end();
+              ++it )
+        {
+            if ( !DoRemove(it->second) )
+               ret = false;
+        }
         m_watches.clear();
-        return true;
+        return ret;
     }
 
     // Check whether any filespec matches the file's ext (if present)