build: comment on why we're not adopting certain flake8 rules
build: comment on why we're not adopting certain flake8 rules

Simplify the list of ignored warnings now that we only have two left,
and document why we're not honouring them.

Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

nertpinx/libvirt,libvirt/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,crobinso/libvirt,olafhering/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,crobinso/libvirt,jardasgit/libvirt,olafhering/libvirt,crobinso/libvirt,zippy2/libvirt,libvirt/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,crobinso/libvirt,fabianfreyer/libvirt,zippy2/libvirt,olafhering/libvirt,zippy2/libvirt,nertpinx/libvirt,jardasgit/libvirt,libvirt/libvirt,zippy2/libvirt,jfehlig/libvirt,nertpinx/libvirt,nertpinx/libvirt,jfehlig/libvirt,libvirt/libvirt,olafhering/libvirt,jardasgit/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,jardasgit/libvirt