haskellPackages.tasty-discover: run test suite in native case

For native compilation, we can just add the intermediary build
directory to `PATH` which allows the test suite to be preprocessed by
tasty-discover itself.

When cross-compiling, `doCheck` will be false anyways and this won't
matter (fingers crossed!).

pkgs/development/haskell-modules/configuration-common.nix

@@ -478,7 +478,11 @@ self: super: {
   doctest-discover = dontCheck super.doctest-discover;
 
   # Depends on itself for testing
-  tasty-discover = dontCheck super.tasty-discover;
+  tasty-discover = overrideCabal super.tasty-discover (drv: {
+    preBuild = ''
+      export PATH="$PWD/dist/build/tasty-discover:$PATH"
+    '' + (drv.preBuild or "");
+  });
 
   # Known issue with nondeterministic test suite failure
   # https://github.com/nomeata/tasty-expected-failure/issues/21