binutils/arc-2014.08: add patch to warn about unsafe library paths

This commit adds a patch to binutils borrowed from CodeSourcery/Yocto
that warns about unsafe library paths (i.e /usr/lib, /usr/local/lib,
etc.). The patch was adapted to binutils arc-2014.08, and modified to
support the BR_COMPILER_PARANOID_UNSAFE_PATH environment variable to
error out instead of just warn when unsafe paths are used. Even though
erroring out can be chosen by passing
--error-poison-system-directories, we are not sure this option in
LDFLAGS will always be passed, so having an environment variable
guarantees it will always be passed, and also allows to have an
identical behavior to the external toolchain wrapper.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Romain Naour <romain.naour@openwide.fr>