- ares_dns.h, missing_header.patch: re-add missing header in last release

- Version update to 1.17.0
Security:
* avoid read-heap-buffer-overflow in ares_parse_soa_reply found during
fuzzing
* Avoid theoretical buffer overflow in RC4 loop comparison
* Empty hquery->name could lead to invalid memory access
* ares_parse_{a,aaaa}_reply() could return a larger *naddrttls than was
passed in (bsc#1178882, CVE-2020-8277)
Changes:
* Update help information for adig, acountry, and ahost
* Test Suite now uses dynamic system-assigned ports rather than hardcoded
ports to prevent failures in containers
* Detect remote DNS server does not support EDNS using rules from RFC 6891
* Source tree has been reorganized to use a more modern layout
* Allow parsing of CAA Resource Record
Bug fixes:
* readaddrinfo bad sizeof()
* Test cases should honor HAVE_WRITEV flag, not depend on WIN32
* FQDN with trailing period should be queried first
* ares_getaddrinfo() was returning members of the struct as garbage values if
unset, and was not honoring ai_socktype and ai_protocol hints.
* ares_gethostbyname() with AF_UNSPEC and an ip address would fail
* Properly document ares_set_local_ip4() uses host byte order
For details, see https://c-ares.haxx.se/changelog.html
- add missing upstream sources, to be removed for next release
- remove unnecessary BuildRequires
- fix building on SLE12 systems