[Skiboot] skiboot-5.1.9 tagged and released!

[Stewart Smith]

skiboot-5.1.9
-------------

skiboot-5.1.9 was released on October 30th, 2015.

skiboot-5.1.9 is the 10th stable release of 5.1, it follows skiboot-5.1.8
(which was released October 19th, 2015).

Skiboot 5.1.9 contains all fixes from skiboot-5.1.8 and is a minor bug
fix release, with a single fix to help diagnosis after a rare error condition.

Over skiboot-5.1.8, we have the following change:
- opal/hmi: Signal PRD about NX unit checkstop.
  We now signal Processor Recovery & Diagnostics (PRD) correctly following
  an NX unit checkstop
- minor fix to the boot_test.sh test script