Like with the network-uri split, cabal will automatically turn off the flag
when building with an old network.
I have not tested building with the new network-3.0.0.0 yet; several
other dependencies including aws are still pinned on network-2.*
And added stack-lts-9.9.yaml to support old versions of stack.
The i386 ancient autobuilder needs stack-lts-9.9.yaml; the OSX autobuilder
may also use it for a while, and it's needed to build on eg debian stable.