This should massively improve performance for (at least) MIPS targets:

    * poly1305: optimize unaligned access

    This is a very appreciated fix from René van Dorst, adjusting the
    arithmetic in Poly1305 to work fast on platforms with slow unaligned
    access, such as MIPS. According to his calculation, this gives a 50%
    improvement on small MIPS boxes.

Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org>

Also fix a new compilation error, due to upstream changes in the build
system.  SUBDIRS= is deprecated when building external kernel modules, use
M= instead to fix compilation.

Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org>

Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org>

Also add the SHA256 checksum, since upstream now publishes it when releasing:

  https://lists.zx2c4.com/pipermail/wireguard/2016-July/000196.html

Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org>

Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org>