wireguard: bump to 0.0.20180904

wireguard: bump to 0.0.20180904

* Kconfig: use new-style help marker
* global: run through clang-format
* uapi: reformat
* global: satisfy check_patch.pl errors
* global: prefer sizeof(*pointer) when possible
* global: always find OOM unlikely

Tons of style cleanups.

* crypto: use unaligned helpers

We now avoid unaligned accesses for generic users of the crypto API.

* crypto: import zinc

More style cleanups and a rearrangement of the crypto routines to fit how this
is going to work upstream. This required some fairly big changes to our build
system, so there may be some build errors we'll have to address in subsequent
snapshots.

* compat: rng_is_initialized made it into 4.19

We therefore don't need it in the compat layer anymore.

* curve25519-hacl64: use formally verified C for comparisons

The previous code had been proved in Z3, but this new code from upstream
KreMLin is directly generated from the F*, which is preferable. The
assembly generated is identical.

* curve25519-x86_64: let the compiler decide when/how to load constants

Small performance boost.

* curve25519-arm: reformat
* curve25519-arm: cleanups from lkml
* curve25519-arm: add spaces after commas
* curve25519-arm: use ordinary prolog and epilogue
* curve25519-arm: do not waste 32 bytes of stack
* curve25519-arm: prefix immediates with #

This incorporates ASM nits from upstream review.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>