In preparation for the deprecation of `stdenv.isX`.
These shorthands are not conducive to cross-compilation because they
hide the platforms.
Darwin might get cross-compilation for which the continued usage of `stdenv.isDarwin` will get in the way
One example of why this is bad and especially affects compiler packages
https://www.github.com/NixOS/nixpkgs/pull/343059
There are too many files to go through manually but a treewide should
get users thinking when they see a `hostPlatform.isX` in a place where it
doesn't make sense.
```
fd --type f "\.nix" | xargs sd --fixed-strings "stdenv.is" "stdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "stdenv'.is" "stdenv'.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "clangStdenv.is" "clangStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "gccStdenv.is" "gccStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "stdenvNoCC.is" "stdenvNoCC.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "inherit (stdenv) is" "inherit (stdenv.hostPlatform) is"
fd --type f "\.nix" | xargs sd --fixed-strings "buildStdenv.is" "buildStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "effectiveStdenv.is" "effectiveStdenv.hostPlatform.is"
fd --type f "\.nix" | xargs sd --fixed-strings "originalStdenv.is" "originalStdenv.hostPlatform.is"
```
The nixpkgs-unstable channel's programs.sqlite was used to identify
packages producing exactly one binary, and these automatically added
to their package definitions wherever possible.
Notably fwupd, pipewire and flatpak.
I want to focus on GNOME and other packages I still actually use.
Pipewire is still important but I have not touched the packaging in a while.
Without the upstream change build fails on toolchains that default to
`-fno-common` (like clang-13 or upstream gcc-10+):
$ nix build --impure --expr 'with import ./.{}; freedroidrpg.override { stdenv = clang13Stdenv; }' -L
...
freedroidrpg> ld: addon_crafting_ui.o:/build/freedroidrpg-0.16.1/src/./struct.h:1025:
multiple definition of `tux_rendering'; action.o:/build/freedroidrpg-0.16.1/src/./struct.h:1025: first defined here
...
Similar to some other builds, sdl-config gets stuck and times out.
checking for sdl-config... /nix/store/q2hm1ka0qxs2gv5bmrxj7j80lygk4b5z-SDL-1.2.15-dev/bin/sdl-config
building of '/nix/store/m2d7v0n5hd2498vfxp18i37p7r1lf76p-freedroidrpg-0.16.1' timed out after 7200 seconds of silence
/cc ZHF #45961
