treewide: replace `stdenv.is` with `stdenv.hostPlatform.is`

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"
```

1 files changed, 3 insertions, 3 deletions

diff --git a/pkgs/by-name/je/jellyfin-web/package.nix b/pkgs/by-name/je/jellyfin-web/package.nix
index c1f81ee3f2f59..ee5622baabd6f 100644
--- a/pkgs/by-name/je/jellyfin-web/package.nix
+++ b/pkgs/by-name/je/jellyfin-web/package.nix
@@ -16,7 +16,7 @@ let
   # node-canvas builds code that requires aligned_alloc,
   # which on Darwin requires at least the 10.15 SDK
   stdenv' =
-    if stdenv.isDarwin then
+    if stdenv.hostPlatform.isDarwin then
       overrideSDK stdenv {
         darwinMinVersion = "10.15";
         darwinSdkVersion = "11.0";
@@ -42,11 +42,11 @@ buildNpmPackage' rec {
 
   npmBuildScript = [ "build:production" ];
 
-  nativeBuildInputs = [ pkg-config ] ++ lib.optionals stdenv.isDarwin [ xcbuild ];
+  nativeBuildInputs = [ pkg-config ] ++ lib.optionals stdenv.hostPlatform.isDarwin [ xcbuild ];
 
   buildInputs =
     [ pango ]
-    ++ lib.optionals stdenv.isDarwin [
+    ++ lib.optionals stdenv.hostPlatform.isDarwin [
       giflib
       darwin.apple_sdk.frameworks.CoreText
     ];