lixPackageSets.*.lix: unbreak cross builds by disabling install checks

Due to an issue [1] in the Python splices uncovered by the setuptools-rust
cross compilation fix [2], some dependencies will otherwise fail to build.
Unfortunately this actually means losing the tests when the build platform
can execute host binaries (such as in `pkgsStatic`), but there's not a lot
one can do about this without fixing the Python splicing.

[1] https://github.com/NixOS/nixpkgs/issues/476822
[2] https://github.com/NixOS/nixpkgs/pull/467817

pkgs/tools/package-management/lix/common-lix.nix

@@ -346,7 +346,8 @@ stdenv.mkDerivation (finalAttrs: {
     rapidcheck
   ];
 
-  doInstallCheck = true;
+  # Python splices are broken (https://github.com/NixOS/nixpkgs/issues/476822), causing build failure in `buildPackages.python3Packages.bcrypt`.
+  doInstallCheck = stdenv.buildPlatform == stdenv.hostPlatform;
   mesonInstallCheckFlags = [
     "--suite=installcheck"
     "--print-errorlogs"