FILES: Do not overwrite and actually remove files_ctx.{pwd,grp}_watch
    
    The snotify_ctx structures were unused, are completely opaque (their
    only value is that if they are freed, the watches disappear which
    the files provider never does).
    
    And moreover, since the patches to support multiple files, the watches
    were overwritten with subsequent assignments.
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>