ProgressMeter for closeAllFiles uses arguments incorrectly

The constructor for ProgressMeter takes two optional string parameters: "units" and "name". "name" is used as the prefix for logged progress reports (default is "Progress") and "units" is displayed in parentheses following the progress percentage if non-empty.

The constructor for ProgressMeter in MongoFile::closeAllFiles() (mmap.cpp) passes "File Closing Progress" in the "units" argument instead of a more appropriate "files" and does not pass an argument for "name".

        ProgressMeter pm(mmfiles.size(), 2, 1, "File Closing Progress");

should be

        ProgressMeter pm(mmfiles.size(), 2, 1, "files", "File Closing Progress");