So the thinking is: anything that needs `haskell-gi-base` is going to
need `gobjectIntrospection` in order to work correctly; by adding this
one `buildDepends` (which therefore gets propagated), we put ourselves
in a position to simplify away a bunch of code in `cabal2nix`.
This reverts commit fd0e0cdc76.
http-streams test suite is no longer broken, but still needs to be
disabled due to cyclic dependencies (http-streams(test) -> snap ->
http-streams)
This reverts commit 17c5ca9018.
This commit causes an evaluation error due to infinite recursion, which can be
tested by running:
```
$ nix-env -f . -qa \* --meta --xml --drv-path --show-trace > /dev/null
```
