Remove the use of GlobalKey

We no longer support syncing tables without primary key, so this can be
removed. However the management of tombstones did somewhat rely on this,
so a more primitive approach where we just make a linear search for
potential tombstone that must be revived. This is  of course slow, but
since this in on the local_only branch, tombstones are only used in some
copy operation.

src/realm/CMakeLists.txt

@@ -47,7 +47,6 @@ set(REALM_SOURCES
     mixed.cpp
     obj.cpp
     object_converter.cpp
-    global_key.cpp
     query_engine.cpp
     query_expression.cpp
     query_value.cpp
@@ -157,7 +156,6 @@ set(REALM_INSTALL_HEADERS
     error_codes.h
     error_codes.hpp
     exceptions.hpp
-    global_key.hpp
     group.hpp
     group_writer.hpp
     handover_defs.hpp

src/realm/cluster_tree.cpp

@@ -991,7 +991,6 @@ void ClusterTree::erase(ObjKey k, CascadeState& state)
             }
         }
     }
-    m_owner->free_local_id_after_hash_collision(k);
     m_owner->erase_from_search_indexes(k);
 
     size_t root_size = m_root->erase(ClusterNode::RowKey(k), state);

src/realm/obj.cpp

@@ -114,11 +114,6 @@ Obj::Obj(TableRef table, MemRef mem, ObjKey key, size_t row_ndx)
     m_storage_version = get_alloc().get_storage_version();
 }
 
-GlobalKey Obj::get_object_id() const
-{
-    return m_table->get_object_id(m_key);
-}
-
 ObjLink Obj::get_link() const
 {
     return ObjLink(m_table->get_key(), m_key);

src/realm/obj.hpp

@@ -34,7 +34,6 @@ class ClusterTree;
 class TableView;
 class CascadeState;
 class ObjList;
-struct GlobalKey;
 
 template <class>
 class Lst;
@@ -100,7 +99,6 @@ class Obj {
     {
         return m_key;
     }
-    GlobalKey get_object_id() const;
     ObjLink get_link() const;
 
     /// Check if the object is still alive