[mono][sgen] Remove mono_gc_clear_domain

It is dead code

src/mono/mono/metadata/boehm-gc.c

@@ -887,11 +887,6 @@ mono_gc_wbarrier_object_copy_internal (MonoObject* obj, MonoObject *src)
 				m_class_get_instance_size (mono_object_class (obj)) - MONO_ABI_SIZEOF (MonoObject));
 }
 
-void
-mono_gc_clear_domain (MonoDomain *domain)
-{
-}
-
 int
 mono_gc_get_suspend_signal (void)
 {

src/mono/mono/metadata/gc-internals.h

@@ -175,7 +175,6 @@ MONO_API int   mono_gc_register_root (char *start, size_t size, MonoGCDescriptor
 MONO_COMPONENT_API void  mono_gc_deregister_root (char* addr);
 void  mono_gc_finalize_domain (MonoDomain *domain);
 void  mono_gc_run_finalize (void *obj, void *data);
-void  mono_gc_clear_domain (MonoDomain * domain);
 
 /*
  * Register a root which can only be written using a write barrier.

src/mono/mono/metadata/sgen-mono.c

@@ -680,41 +680,6 @@ mono_gc_ephemeron_array_add (MonoObject *obj)
 	return TRUE;
 }
 
-/*
- * When appdomains are unloaded we can easily remove objects that have finalizers,
- * but all the others could still be present in random places on the heap.
- * We need a sweep to get rid of them even though it's going to be costly
- * with big heaps.
- * The reason we need to remove them is because we access the vtable and class
- * structures to know the object size and the reference bitmap: once the domain is
- * unloaded the point to random memory.
- */
-void
-mono_gc_clear_domain (MonoDomain * domain)
-{
-	LOCK_GC;
-
-	sgen_binary_protocol_domain_unload_begin (domain);
-
-	sgen_stop_world (0, FALSE);
-
-	sgen_process_fin_stage_entries ();
-
-	sgen_clear_nursery_fragments ();
-
-	if (domain == mono_get_root_domain ()) {
-		sgen_pin_stats_report ();
-		sgen_object_layout_dump (stdout);
-	}
-
-	sgen_restart_world (0, FALSE);
-
-	sgen_binary_protocol_domain_unload_end (domain);
-	sgen_binary_protocol_flush_buffers (FALSE);
-
-	UNLOCK_GC;
-}
-
 /*
  * Allocation
  */