wireguard-tools: bump to 1.0.20200827

wireguard-tools: bump to 1.0.20200827

* ipc: split into separate files per-platform

This is in preparation for FreeBSD support, which I had hoped to have this
release, but we're still waiting on some tooling fixes, so hopefully next
wg(8) will support that. Either way, the code base is now a lot more amenable
to adding more kernel platform support.

* man: wg-quick: use syncconf instead of addconf for strip example

Simple documentation fix.

* pubkey: isblank is a subset of isspace
* ctype: use non-locale-specific ctype.h

In addition to ensuring that isalpha() and such isn't locale-specific, we also
make these constant time, even though we're never distinguishing between bits
of a secret using them. From that perspective, though, this is markedly better
than the locale-specific table lookups in glibc, even though base64 characters
span two cache lines and valid private keys must hit both. This may be useful
for other projects too: https://git.zx2c4.com/wireguard-tools/tree/src/ctype.h

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