The old stdenv adapters were subtly wrong in two ways:
- `overrideAttrs` leaked the original, unoverridden `mkDerivation`.
- `stdenv.override` would throw away any manually-set `mkDerivation`
from a stdenv reverting to the original.
Now, `mkDerivation` is controlled (nearly directly) via an argument, and
always correctly closes over the final ("self") stdenv. This means the
adapters can work entirely via `.override` without any manual `stdenv //
...`, and both those issues are fixed.
Note hashes are changed, because stdenvs no previously overridden like
`stdenvNoCC` and `crossLibcStdenv` now are. I had to add some
`dontDisableStatic = true` accordingly. The flip side however is that
since the overrides compose, we no longer need to override anything but
the default `stdenv` from which all the others are created.
f110a182a6