fix(build): add missing file

src/util/memory_pool.cpp

@@ -0,0 +1,53 @@
+/*
+Copyright (c) 2014 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#include <vector>
+#include "util/thread.h"
+#include "util/memory_pool.h"
+
+namespace lean {
+memory_pool::~memory_pool() {
+    while (m_free_list != nullptr) {
+        void * r = m_free_list;
+        m_free_list = *(reinterpret_cast<void **>(r));
+        free(r);
+    }
+}
+
+void * memory_pool::allocate() {
+    if (m_free_list != nullptr) {
+        void * r = m_free_list;
+        m_free_list = *(reinterpret_cast<void **>(r));
+        return r;
+    } else {
+        return malloc(m_size);
+    }
+}
+
+typedef std::vector<memory_pool*> memory_pools;
+LEAN_THREAD_PTR(memory_pools, g_thread_pools);
+
+static void thread_finalize_memory_pool() {
+    if (g_thread_pools) {
+        unsigned i = g_thread_pools->size();
+        while (i > 0) {
+            --i;
+            delete (*g_thread_pools)[i];
+        }
+        delete g_thread_pools;
+    }
+}
+
+memory_pool * allocate_thread_memory_pool(unsigned sz) {
+    if (!g_thread_pools) {
+        register_post_thread_finalizer(thread_finalize_memory_pool);
+        g_thread_pools = new std::vector<memory_pool*>();
+    }
+    memory_pool * r = new memory_pool(sz);
+    g_thread_pools->push_back(r);
+    return r;
+}
+}