Update (disk)scrub to 2.5.2 (+add DIOCGDISKINFO implementation)

Since 2.0:
* Fix scrub abort on files/disks > 2G in size (issue 19)
  This was introduced in 2.5.0 and the failure is quick and obvious.
* Fix loss of precision in disk size approximation (issue 18)
* Add -t option to disable creation of thread to generate randomness
  in parallel with I/O.
* Prepare source for a libscrub api (work in progress)
* Cosmetic changes to man page and help output.
* Generate randomness and do I/O in parallel [Richard B. Hill]
* Replace O_SYNC with O_DIRECT+fsync+posix_fadvise [H. Peter Anvin]
  This produces a significant performance improvement, at least on Linux.
* Add support for RDRAND instr. [H. Peter Anvin]
* Use <stdbool.h> if the system has it [H. Peter Anvin]
* Fix incorrect assertion in scrub --dirent handling (issue 9) [Peter Hyman]
* Clean up tmp files after scrub --freespace (issue 9) [Peter Hyman]
* Allow scrub --pattern=custom="string" (issue 11) [Peter Hyman]
  Allow C style numerical escapes in string: \nnn (octal) and \xnn (hex).
  This is a single-pass sequence with a custom pattern.
* Change default buffer size from 1m to 4m [H. Peter Anvin]
* Avoid closing and re-opening /dev/urandom [H. Peter Anvin]
* Fix bug in pfitzner7 pattern def and add fillff, fillzero
  methods (issue 8) [Peter Hyman]
* Change dod method to perform random pass first and skip extra pass.
* Add --help option that lists available scrub methods.
* Make dist tarball work with rpmbuild -ta.
* Added usarmy, pfitzner7, and pfitzner33 methods.
* Added -L option to not follow symbolic links [Timothy Boronczyk]
* Treat a zero return from write(2) as an error.
* New patterns:
  - random2: two random passes
  - schneier (one 0x00 pass, one 0xff pass, and five random passes) [Joe]
* Add --pattern random (one random pass) mode.
* Portability fixes for Slackware [Timothy Boronczyk]
* Fix bug where scrub --remove on a zero length file would abort
  without removing the file.  Issue a warning and remove it.
* Fix a bug where some data from the original file could appear in
  the first disk block after a verified scrub when running without
  the -S (--no-signature) option.

(prlw1)