gdb: backport upstream libiberty patch

This backports an upstream libiberty patch to
make gdb build with clang.
The upsteam patch is at gcc tree
commit 19ecc7c1742ebd58f7b940da6cee3c6891020f1e
Author: ian <ian@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Fri May 22 20:53:45 2015 +0000

BUG=chromium:475970
TEST=emerge sys-devel/gdb works.

Change-Id: I48aad52accc4f46ceb836907e169dd4eb841df3a
Reviewed-on: https://chromium-review.googlesource.com/274076
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
6 files changed