buildFHSEnv: fix cross compilation

In particular, steam aarch64-linux -> x86_64-linux cross did not compile
before.

pkgs/build-support/build-fhsenv-bubblewrap/buildFHSEnv.nix

@@ -5,7 +5,7 @@
 , writeText
 , writeShellScriptBin
 , pkgs
-, pkgsi686Linux
+, pkgsHostTarget
 }:
 
 { profile ? ""
@@ -36,6 +36,10 @@
 # /lib will link to /lib64
 
 let
+  # The splicing code does not handle `pkgsi686Linux` well, so we have to be
+  # explicit about which package set it's coming from.
+  inherit (pkgsHostTarget) pkgsi686Linux;
+
   name = if (args ? pname && args ? version)
     then "${args.pname}-${args.version}"
     else args.name;
@@ -212,7 +216,7 @@ let
         ln -fsr $d/glib-2.0/schemas/*.xml $out/usr/share/glib-2.0/schemas
         ln -fsr $d/glib-2.0/schemas/*.gschema.override $out/usr/share/glib-2.0/schemas
       done
-      ${pkgs.glib.dev}/bin/glib-compile-schemas $out/usr/share/glib-2.0/schemas
+      ${pkgs.pkgsBuildBuild.glib.dev}/bin/glib-compile-schemas $out/usr/share/glib-2.0/schemas
     fi
 
     ${extraBuildCommands}

pkgs/build-support/build-fhsenv-bubblewrap/default.nix

@@ -4,7 +4,7 @@
 , runCommandLocal
 , writeShellScript
 , glibc
-, pkgsi686Linux
+, pkgsHostTarget
 , runCommandCC
 , coreutils
 , bubblewrap
@@ -42,6 +42,10 @@ let
 
   inherit (lib.attrsets) removeAttrs;
 
+  # The splicing code does not handle `pkgsi686Linux` well, so we have to be
+  # explicit about which package set it's coming from.
+  inherit (pkgsHostTarget) pkgsi686Linux;
+
   name = args.name or "${args.pname}-${args.version}";
   executableName = args.pname or args.name;
   # we don't know which have been supplied, and want to avoid defaulting missing attrs to null. Passed into runCommandLocal