[PATCH 3/3, newlib] Allow locking routine to be retargeted

[Freddie Chopin]

On Thu, 2017-02-02 at 10:21 +0000, Thomas Preudhomme wrote:
> Ooops, forgot about this. Please find an updated patch attached.

OK, I happily confirm that everything works fine now. I've applied 3
relevant patches:

0001-Unify-names-of-all-lock-objects.patch
guard_static_lock_single_thread.patch
newlib_retargetable_locking_routine.patch

The toolchain builds fine (including HTML and PDF documentation) and
works as expected, allowing the locking functions to be provided by
user. I have tested toolchain with and without the new "--enable-
newlib-retargetable-locking" option.

Regards,
FCh