Switching `pkg` to HTTPS by default

[Andrew Savchenko]

Hello,

I have added the following snippet under the 
/usr/local/etc/pkg/repos/FreeBSD.conf:

```
FreeBSD: {
  url: "pkg+https://pkg.FreeBSD.org/${ABI}/quarterly",
  mirror_type: "srv",
  signature_type: "fingerprints",
  fingerprints: "/usr/share/keys/pkg",
  enabled: yes
}
```

Note the "https" part of the address. Regardless, `pkg` continued fetching 
binaries over unencrypted http. I had to change the /etc/pkg/FreeBSD.conf for 
this to have any effect.

Setting `VULNXML_SITE` to HTTPS in /usr/local/etc/pkg.conf worked as expected.

Is this a valid bug to report over to freebsd-bugs at freebsd.org?


-- 
Regards,
A