Add tagSocket/untagSocket NDK APIs

Provide native APIs to tag the various sockets used for network
transfer, which helps apps tracking down data usage inside their app.

We've had equivalent Java APIs since API level 14.
https://developer.android.com/reference/android/net/TrafficStats.html#tagSocket(java.net.Socket)
https://developer.android.com/reference/android/net/TrafficStats.html#untagSocket(java.net.Socket)

Given that these Java APIs are implemented in native side, providing
NDK APIs directly will be easier for native users to use it.

Bug: 29761778
Bug: 202086915
Test: Tests in change Ic6554d9b98cef9b41b7eae06315d284c574c0a45
Change-Id: I802ce62f82199ce087bf8feb03afb26de1ce526e

native/android/libandroid_net.map.txt

@@ -18,6 +18,10 @@ LIBANDROID_NET {
     android_getprocnetwork; # llndk
     android_setprocdns; # llndk
     android_getprocdns; # llndk
+    # These functions have been part of the NDK since API 33.
+    android_tag_socket_with_uid; # llndk
+    android_tag_socket;  # llndk
+    android_untag_socket; # llndk
   local:
     *;
 };

native/android/net.c

@@ -161,3 +161,15 @@ int android_res_nsend(net_handle_t network, const uint8_t *msg, size_t msglen,
 void android_res_cancel(int nsend_fd) {
     resNetworkCancel(nsend_fd);
 }
+
+int android_tag_socket_with_uid(int sockfd, int tag, uid_t uid) {
+    return tagSocket(sockfd, tag, uid);
+}
+
+int android_tag_socket(int sockfd, int tag) {
+    return tagSocket(sockfd, tag, -1);
+}
+
+int android_untag_socket(int sockfd) {
+    return untagSocket(sockfd);
+}