[PATCH] libiberty: sync with gcc

[Nick Clifton]

Hi Matthieu,

> Import the following commits from GCC as of r16-2170-g2f2e9bcfb0fd9c:
> 	0fd98b6f9f2 libiberty: add routines to handle type-sensitive doubly linked lists

Approved - please apply - mainline only.

Cheers
   Nick