binutils: add support for binutils 2.29

All patches from binutils 2.28 are kept, except patch
0906-microblaze-pr21180.patch, because it has been merged upstream as
of commit bd757ca7bf5886a4025ca02093fca1b8c5ce11a2. Other patches are
slightly adapted to differences that appeared in binutils 2.29.

The patches are now all Git formatted, so instead of having weird
sequence numbers, they have normal sequence numbers starting from 0001
and incrementing.

Since binutils 2.29 is now available as a .tar.xz tarball, we use this
format instead of .bz2 used for previous versions.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>