toolchain/binutils: Improve arm linking performance

Backported a patch from CVS that improves linking times for large
projects (eg 700s to 6s). See
http://old.nabble.com/-PATCH--Reduce-ARM-linking-time-tt27961038.html


for the original.

[Peter: add patch header]
Signed-off-by: Laine Walker-Avina <lwalkera@ieee.org>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>