Add wasm_runtime_unregister_natives (#1647)

Allow to unregister (or unload) the previously registered native libs,
so that no need to restart the whole engine by using
`wasm_runtime_destroy/wasm_runtime_init`.

core/iwasm/common/wasm_runtime_common.c

@@ -2904,6 +2904,13 @@ wasm_runtime_register_natives_raw(const char *module_name,
                                             n_native_symbols);
 }
 
+bool
+wasm_runtime_unregister_natives(const char *module_name,
+                                NativeSymbol *native_symbols)
+{
+    return wasm_native_unregister_natives(module_name, native_symbols);
+}
+
 bool
 wasm_runtime_invoke_native_raw(WASMExecEnv *exec_env, void *func_ptr,
                                const WASMType *func_type, const char *signature,