Use HTTPS to securely download the source archive.

*   1.6.0 (Date: 15 Dec, 2016)

> Features

> *   Added generic EDNS code for registering known EDNS option codes,
> bypassing the cache response stage and uniquifying mesh states. Four
> EDNS option lists were added to module_qstate
> (module_qstate.edns_opts_*) to store EDNS options from/to front/back
> side.
> *   Added two flags to module_qstate (no_cache_lookup, no_cache_store)
> that control the modules' cache interactions.
> *   Added code for registering inplace callback functions. The
> registered functions can be called just before replying with local data
> or Chaos, replying from cache, replying with SERVFAIL, replying with a
> resolved query, sending a query to a nameserver. The functions can
> inspect the available data and maybe change response/query related data
> (i.e. append EDNS options).
> *   Updated Python module for the above.
> *   Updated Python documentation.
> *   Added views functionality.
> *   Added qname-minimisation-strict config option.
> *   Patch that resolves CNAMEs entered in local-data conf statements
> that point to data on the internet, from Jinmei Tatuya (Infoblox).
> *   serve-expired config option: serve expired responses with TTL 0.
> *   .gitattributes line for githubs code language display.
> *   log-identity: config option to set sys log identity, patch from
> "Robin H. Johnson" (robbat2@gentoo.org).
> *   Added stub-ssl-upstream and forward-ssl-upstream options.
> *   Added local-zones and local-data bulk addition and removal
> functionality in unbound-control (local_zones, local_zones_remove,
> local_datas and local_datas_remove).

*   1.6.3 (13 Jun, 2017)

> Fix #1280: Unbound fails assert when response from authoritative
> contains malformed qname. When 0x20 caps-for-id is enabled, when
> assertions are not enabled the malformed qname is handled correctly.

[1] https://www.unbound.net/download.html

This reverts commit 5876741.

Unbound expects at least systemd 209 with libsystemd. Currently systemd
27 is installed, so the check fails.

```
checking for SYSTEMD... no
checking for SYSTEMD_DAEMON... no
```

Currently, there is a bug in the test suite, when building out of the
source tree. Making the test data available, in this case with a
symbolic link, works around the problem.

> When doing an out of source build of Unbound, the test suite fails
> with the error below.
>
> ```
> test signature verify functions
> testpkts error: could not open file testdata/test_signatures.1: No such
> file or directory
> Makefile:304: recipe for target 'test' failed
> make: *** [test] Error 1
> ```
>
> The reason is, that `testcode/unitverify.c` references files in a
> relative way.
>
> ```
> […]
> void
> verify_test(void)
> {
>         unit_show_feature("signature verify");
> #ifdef USE_SHA1
>         verifytest_file("testdata/test_signatures.1", "20070818005004");
> #endif
> #if defined(USE_DSA) && defined(USE_SHA1)
>         verifytest_file("testdata/test_signatures.2", "20080414005004");
> […]
> ```
>
> Unfortunately, I don’t know what the recommended way in that case is.
> Copy the test data to the build directory, link to it, or use absolute
> paths.

> --with-rootkey-file=filename set default pathname to root key file
> (default run-dir/root.key). This file is read and written.

>  --with-pidfile=filename set default pathname to unbound pidfile
>  (default run-dir/unbound.pid)

In our environment, the  configuration file is adapted, and distributed
from our distmaster. So don’t override it in the package.