Ignore nullptr in native_handle_close().

Just like native_handle_delete().

Bug: http://b/143898343
Test: new test
Change-Id: I373067aa6c2b03548b218c7011bdbf23bd71f260

libcutils/Android.bp

@@ -197,7 +197,10 @@ cc_library {
 
 cc_defaults {
     name: "libcutils_test_default",
-    srcs: ["sockets_test.cpp"],
+    srcs: [
+        "native_handle_test.cpp",
+        "sockets_test.cpp",
+    ],
 
     target: {
         android: {

libcutils/native_handle.cpp

@@ -81,6 +81,8 @@ int native_handle_delete(native_handle_t* h) {
 }
 
 int native_handle_close(const native_handle_t* h) {
+    if (!h) return 0;
+
     if (h->version != sizeof(native_handle_t)) return -EINVAL;
 
     int saved_errno = errno;

libcutils/native_handle_test.cpp

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <cutils/native_handle.h>
+
+#include <gtest/gtest.h>
+
+TEST(native_handle, native_handle_delete) {
+    ASSERT_EQ(0, native_handle_delete(nullptr));
+}
+
+TEST(native_handle, native_handle_close) {
+    ASSERT_EQ(0, native_handle_close(nullptr));
+}