chez: add env hook

As a follow-up to #97927, chez can now find its libraries in a
nix-shell, and derivations for such libraries don't need to handle the
search path themselves.

pkgs/development/chez-modules/chez-mit/default.nix

@@ -13,7 +13,6 @@ stdenv.mkDerivation {
   buildInputs = [ chez chez-srfi ];
 
   buildPhase = ''
-    export CHEZSCHEMELIBDIRS=${chez-srfi}/lib/csv-site
     make PREFIX=$out CHEZ=${chez}/bin/scheme
   '';
 

pkgs/development/chez-modules/chez-scmutils/default.nix

@@ -13,7 +13,6 @@ stdenv.mkDerivation {
   buildInputs = [ chez chez-srfi chez-mit ];
 
   buildPhase = ''
-    export CHEZSCHEMELIBDIRS=${chez-srfi}/lib/csv-site:${chez-mit}/lib/csv-site
     make PREFIX=$out CHEZ=${chez}/bin/scheme
   '';
 

pkgs/development/compilers/chez/default.nix

@@ -65,6 +65,8 @@ stdenv.mkDerivation rec {
     rm -rf $out/lib/csv${version}/examples
   '';
 
+  setupHook = ./setup-hook.sh;
+
   meta = {
     description  = "A powerful and incredibly fast R6RS Scheme compiler";
     homepage     = "https://cisco.github.io/ChezScheme/";

pkgs/development/compilers/chez/setup-hook.sh

@@ -0,0 +1,5 @@
+addChezLibraryPath() {
+  addToSearchPath CHEZSCHEMELIBDIRS "$1/lib/csv-site"
+}
+
+addEnvHooks "$targetOffset" addChezLibraryPath