[fesco] Updated FTBFS package policy

[Zbigniew Jędrzejewski-Szmek]

Fedora package maintainers,

FESCo approved an updated policy for packages which fail to build from
source during mass rebuilds (FTBFS) [1].

The updated policy is still at https://fedoraproject.org/wiki/Fails_to_build_from_source.

Highlights:

- packages which FTBFS are subject to orphaning if there is no
  maintainer acknowledgement within 8 weeks

- packages which FTBFS in two consecutive mass rebuilds will be
  retired soon after the second mass rebuild

The implementation of this policy hinges on improving the releng
scripts used to create and manage FTBFS bugs. There is approximately
two months until the next use of those scripts, so I'm hopeful we'll
get them working.

If your package wasn't successfully built for F28, please fix that!

[1] https://pagure.io/fesco/issue/1890
[2] https://pagure.io/fesco/issue/1877#comment-509161