This commit has been generated by maintainers/scripts/haskell/update-stackage.sh

This commit has been generated by maintainers/scripts/haskell/update-hackage.sh

This commit has been generated by maintainers/scripts/haskell/regenerate-hackage-packages.sh

haskellPackages.entropy: build with js backend

This is easy in comparison since these tools won't end up in GHC's
settings nor need to be available at runtime, so we can use
the *_FOR_BUILD environment variables.

It is important to add buildCC to depsBuildBuild to engage the
stdenv/wrapper script machinery properly.

Co-authored-by: sternenseemann <[email protected]>

1. Explicitly set WITH_TERMINFO. We usually match GHC's behavior well,
   but it is better to tie the Nix option to make explicitly.
   Unfortunately, the same is very complicated to achieve with
   hadrian (iirc).
2. Disable enableTerminfo if we are cross-compiling. This matches
   the behavior of GHC's build system, so we'll have to match it now.
   It also reduces the ncurses-related headache a bit.
3. Stop passing --with-curses* flags. Unfortunately, GHC does not
   account for the fact that different platforms need different ncurses
   libraries. This is somewhat migitated by the fact that ncurses is
   only ever needed for the build platform if we are cross compiling,
   but I seem to remember it leaking into the final GHC somehow.
   A more reliable alternative is relying on the cc/ld wrapper scripts,
   as they'll always pull out the correct ncurses out of the environment
   when GHC's build system passes -lcurses.
4. Unconditionally add ncurses to depsBuildBuild. Stage0 unconditionally
   builds terminfo (maybe the stage1 compiler needs it?), so we need to
   make sure that ncurses for the build platform is available.

Co-authored-by: sternenseemann <[email protected]>

Propagating the supported platforms of the boot compiler doesn't make
much sense when unregistered cross-compilation is possible.

This is to ensure that Haskell users on platforms that lack official
bindists still have a convenient means of getting GHC running natively.

In my admittedly somewhat limited testing on RISC-V, GHC 8.10.7 is able
to bootstrap native builds for 9.2.8 and 9.4.5. GHC 9.2.8 and 9.4.5 are
unable to bootstrap themselves and 9.6.2 when cross-compiled.

If you're looking at this commit to see whether you can safely upgrade
the compiler used here to remove 8.10, please try cross-compiling 9.0 or
later and then booting a native GHC with it.