Emacs c-X c-W doesn't increment the "number of writes to file" fdb halfword

[Chris Lindblad <CJL%MIT-OZ@MIT-MC.ARPA>]

When I c-X c-W to an existing file, the "number of writes to file" fdb
halfword for the file is not incremented. This is bad, because DUMPER
won't know that it needs to be backed up again.