Also begin to start work on cross compilation, though that will have to
be finished later.
The patches are based on the first version of
https://reviews.llvm.org/D99484. It's very annoying to do the
back-porting but the review has uncovered nothing super major so I'm
fine sticking with what I've got.
Beyond making the outputs work, I also strove to re-sync the packages,
as they have been drifting pointlessly apart for some time.
----
Other misc notes, highly incomplete
- lvm-config-native and llvm-config are put in `dev` because they are
tools just for build time.
- Clang no longer has an lld dep. That was introduced in
db29857eb3, but if clang needs help
finding lld when it is used we should just pass it flags / put in the
resource dir. Providing it at build time increases critical path
length for no good reason.
----
A note on `nativeCC`:
`stdenv` takes tools from the previous stage, so:
1. `pkgsBuildBuild`: `(?1, x, x)`
2. `pkgsBuildBuild.stdenv.cc`: `(?0, ?1, x)`
while:
1. `pkgsBuildBuild`: `(?1, x, x)`
2. `pkgsBuildBuild.targetPackages`: `(x, x, ?2)`
3. `pkgsBuildBuild.targetPackages.stdenv.cc`: `(?1, x, x)`
Without this change `as` on `aarch64-darwin` is defunct:
```
$ /nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/bin/as -v
/nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/bin/as: assembler (/nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/libexec/as/arm64/as or /nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/libexec/as/arm64/as) for architecture arm64 not installed
Installed assemblers are:
/nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/libexec/as/ppc64/as for architecture ppc64
/nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/libexec/as/x86_64/as for architecture x86_64
/nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/libexec/as/ppc/as for architecture ppc
/nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/libexec/as/i386/as for architecture i386
/nix/store/g11xba8ch20zndaf32hfnap46z47b5k3-cctools-port-949.0.1/libexec/as/arm/as for architecture arm
```
Apple defaults to Clang in all cases from what I see, but nixpkgs prefers `cctools`: #51881.