openshadinglanguage: move override to package.nix

This is a step towards https://redirect.github.com/NixOS/nixpkgs/pull/483820,
which will help enable checking for additional by-name directories
(e.g. Python) in nixpkgs-vet.

For more information, please see https://redirect.github.com/NixOS/nixpkgs/pull/483859#issuecomment-3799768711.

pkgs/by-name/op/openshadinglanguage/package.nix

@@ -1,14 +1,12 @@
 {
   bison,
   boost,
-  clang,
   cmake,
   fetchFromGitHub,
   flex,
   lib,
-  libclang,
   libxml2,
-  llvm,
+  llvmPackages_19,
   openexr,
   openimageio,
   partio,
@@ -22,6 +20,7 @@
 
 let
   boost_static = boost.override { enableStatic = true; };
+  inherit (llvmPackages_19) clang libclang llvm;
 in
 stdenv.mkDerivation (finalAttrs: {
   pname = "openshadinglanguage";

pkgs/top-level/all-packages.nix

@@ -3160,12 +3160,6 @@ with pkgs;
 
   update-systemd-resolved = callPackage ../tools/networking/openvpn/update-systemd-resolved.nix { };
 
-  openshadinglanguage = callPackage ../by-name/op/openshadinglanguage/package.nix {
-    libclang = llvmPackages_19.libclang;
-    clang = clang_19;
-    llvm = llvm_19;
-  };
-
   opentelemetry-collector = opentelemetry-collector-releases.otelcol;
   opentelemetry-collector-builder = callPackage ../tools/misc/opentelemetry-collector/builder.nix { };
   opentelemetry-collector-contrib = opentelemetry-collector-releases.otelcol-contrib;