Revert "Revert "Revert "Rely on conservative stack scanning to find "emacs_value"s"""

This reverts commit 093d3e78,
which reverted ee7ad83f,
which reverted 3eb93c07.

test/data/emacs-module/mod-test.c

@@ -94,7 +94,7 @@ Fmod_test_signal (emacs_env *env, ptrdiff_t nargs, emacs_value args[],
   assert (env->non_local_exit_check (env) == emacs_funcall_exit_return);
   env->non_local_exit_signal (env, env->intern (env, "error"),
 			      env->make_integer (env, 56));
-  return env->intern (env, "nil");
+  return NULL;
 }
 
 
@@ -106,7 +106,7 @@ Fmod_test_throw (emacs_env *env, ptrdiff_t nargs, emacs_value args[],
   assert (env->non_local_exit_check (env) == emacs_funcall_exit_return);
   env->non_local_exit_throw (env, env->intern (env, "tag"),
 			     env->make_integer (env, 65));
-  return env->intern (env, "nil");
+  return NULL;
 }
 
 
@@ -304,7 +304,7 @@ Fmod_test_invalid_finalizer (emacs_env *env, ptrdiff_t nargs, emacs_value *args,
 {
   current_env = env;
   env->make_user_ptr (env, invalid_finalizer, NULL);
-  return env->funcall (env, env->intern (env, "garbage-collect"), 0, NULL);
+  return env->intern (env, "nil");
 }
 
 static void

test/src/emacs-module-tests.el

@@ -265,7 +265,8 @@ during garbage collection."
   (skip-unless (file-executable-p mod-test-emacs))
   (module--test-assertion
       (rx "Module function called during garbage collection\n")
-    (mod-test-invalid-finalizer)))
+    (mod-test-invalid-finalizer)
+    (garbage-collect)))
 
 (ert-deftest module/describe-function-1 ()
   "Check that Bug#30163 is fixed."