return when can't read the cwd

svn path=/branches/KDE/3.5/kdepim/; revision=489791

kmfoldermaildir.cpp

@@ -620,7 +620,9 @@ void KMFolderMaildir::readFileHeaderIntern(const QString& dir, const QString& fi
 {
   // we keep our current directory to restore it later
   char path_buffer[PATH_MAX];
-  ::getcwd(path_buffer, PATH_MAX - 1);
+  if(::getcwd(path_buffer, PATH_MAX - 1))
+    return;
+
   ::chdir(QFile::encodeName(dir));
 
   // messages in the 'cur' directory are Read by default.. but may