scripts/install-info.pl: Several fixes:

scripts/install-info.pl: Several fixes:
  * Move /usr/info/dir to /usr/share/info/dir.
  * Improve message when locking and /usr/share/info/dir doesn't exist.
  * Use /var/backups/infodir.bak if the above doesn't exist.
  * Allow for relative filenames, and add a --remove-exactly option.
  * Use section from the .info file if --section is not given.
  * Include current filename in error messages.
  * Format /usr/share/info/dir entries to uniform width.
  * --calign|--align|--maxwidth are now ignored.