[WireGuard] wg doesn't build on 4.7 kernels

[Bruno Wolff III]

On Wed, Jun 29, 2016 at 22:48:26 +0200,
  "Jason A. Donenfeld" <Jason at zx2c4.com> wrote:
>Fixed here:
>https://git.zx2c4.com/WireGuard/commit/?id=530ee2b2906af4d635d4d5bbabda5250b4a2b33e

That fixed the reported problem, but another 4.7 change is causing problems.
See: https://www.spinics.net/lists/kernel/msg2233003.html

These are the errors:
/home/bruno/WireGuard/src/crypto/chacha20poly1305.c: In function ‘chacha20poly1305_init’:
/home/bruno/WireGuard/src/crypto/chacha20poly1305.c:40:30: error: ‘cpu_has_xmm2’ undeclared (first use in this function)
  chacha20poly1305_use_sse2 = cpu_has_xmm2;
                              ^~~~~~~~~~~~
/home/bruno/WireGuard/src/crypto/chacha20poly1305.c:40:30: note: each undeclared identifier is reported only once for each function it appears in
/home/bruno/WireGuard/src/crypto/chacha20poly1305.c:42:30: error: ‘cpu_has_avx’ undeclared (first use in this function)
  chacha20poly1305_use_avx2 = cpu_has_avx && cpu_has_avx2 &&
                              ^~~~~~~~~~~
/home/bruno/WireGuard/src/crypto/chacha20poly1305.c:42:45: error: ‘cpu_has_avx2’ undeclared (first use in this function)
  chacha20poly1305_use_avx2 = cpu_has_avx && cpu_has_avx2 &&
                                             ^~~~~~~~~~~~
scripts/Makefile.build:289: recipe for target '/home/bruno/WireGuard/src/crypto/chacha20poly1305.o' failed
make[2]: *** [/home/bruno/WireGuard/src/crypto/chacha20poly1305.o] Error 1
Makefile:1461: recipe for target '_module_/home/bruno/WireGuard/src' failed
make[1]: *** [_module_/home/bruno/WireGuard/src] Error 2
make[1]: Leaving directory '/usr/src/kernels/4.7.0-0.rc5.git1.2.fc25.x86_64'
Makefile:34: recipe for target 'module' failed
make: *** [module] Error 2