profiles/thirpartymirrors: Modify hackage mirrors for #644382
The hackport mirrors in profiles/thirdpartymirrors have two problems:
1. `hackage.haskell.org` supports HTTPS and so this URL should be
switched to `https://hackage.haskell.org/`
2. The second mirror is currently redirecting all requests to
`http://hdiff.luite.com/`. `hdiff.luite.com` does not have working
HTTPS and so this second mirror should be removed as it misleads
devs into thinking this mirror will provide encryption.
Closes: https://bugs.gentoo.org/644382
Closes: https://github.com/gentoo/gentoo/pull/6850