[NETD-BPF#1] Move libnetdutils to frameworks/libs/net/...

libnetdutils is referenced by netd.c and TrafficController.cpp, which
are going to be mainlined. Therefore, move libnetdutils to a common
place where both mainline module and platform code (Netd) can refer to.

Bug: 202086915
Test: build; flash; cd system/netd; atest
Ignore-AOSP-First: the netd change(same topic) would not automerge from
aosp.
No-Typo-Check: Clean code move with no other changes.
BYPASS_INCLUSIVE_LANGUAGE_REASON=Clean code move with no other changes.
Change-Id: I645bfe35f6543149c9a9f894cd4158d27a481abe

staticlibs/netd/libnetdutils/include/netdutils/Math.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#ifndef NETUTILS_MATH_H
+#define NETUTILS_MATH_H
+
+#include <algorithm>
+#include <cstdint>
+
+namespace android {
+namespace netdutils {
+
+template <class T>
+inline constexpr const T mask(const int shift) {
+    return (1 << shift) - 1;
+}
+
+// Align x up to the nearest integer multiple of 2^shift
+template <class T>
+inline constexpr const T align(const T& x, const int shift) {
+    return (x + mask<T>(shift)) & ~mask<T>(shift);
+}
+
+}  // namespace netdutils
+}  // namespace android
+
+#endif /* NETUTILS_MATH_H */