utest: move cpp from examples to components/libc/cplusplus

Also update the case names to compatible with naming rules.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>

components/libc/cplusplus/utest/tc_auto.cpp

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2006-2025, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2025-09-19     Rbb666       the first version
+ */
+
+#include <rtthread.h>
+#include "utest.h"
+#include <vector>
+
+/**
+ * @brief Test auto keyword.
+ */
+static void test_auto(void)
+{
+    auto x = 42;
+    auto y = 3.14;
+    if (x != 42 || y != 3.14)
+    {
+        uassert_false(true);
+    }
+    uassert_true(true);
+}
+
+/**
+ * @brief Test range-based for loop.
+ */
+static void test_range_for(void)
+{
+    std::vector<int> v = {1, 2, 3, 4, 5};
+    int sum = 0;
+    for (auto i : v)
+    {
+        sum += i;
+    }
+    if (sum != 15)
+    {
+        uassert_false(true);
+    }
+    uassert_true(true);
+}
+
+static rt_err_t utest_tc_init(void)
+{
+    return RT_EOK;
+}
+
+static rt_err_t utest_tc_cleanup(void)
+{
+    return RT_EOK;
+}
+
+static void testcase(void)
+{
+    /* Test auto keyword */
+    UTEST_UNIT_RUN(test_auto);
+    /* Test range-based for loop */
+    UTEST_UNIT_RUN(test_range_for);
+}
+UTEST_TC_EXPORT(testcase, "components.libc.cpp.auto_tc", utest_tc_init, utest_tc_cleanup, 10);