添加rtthread相关代码

riscv/rtthread/components/libc/posix/libdl/dlclose.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2010-11-17     yi.qiu       first version
+ */
+
+#include <rtthread.h>
+#include <rtm.h>
+
+#include "dlmodule.h"
+
+int dlclose(void *handle)
+{
+    struct rt_dlmodule *module;
+
+    RT_ASSERT(handle != RT_NULL);
+
+    module = (struct rt_dlmodule *)handle;
+
+    rt_enter_critical();
+    module->nref--;
+    if (module->nref <= 0)
+    {
+        rt_exit_critical();
+
+        dlmodule_destroy(module);
+    }
+    else
+    {
+        rt_exit_critical();
+    }
+
+    return RT_TRUE;
+}
+RTM_EXPORT(dlclose)