Use libnetjniutils for JNI File Descriptor info

Drops use of deprecated API in libnativehelper and uses a common
helper that will be stable across releases.

Bug: 158749603
Test: m
Change-Id: Ic1a1811ffb9a1c207f562a180417e99df31e3502

Tethering/Android.bp

@@ -67,6 +67,9 @@ cc_library {
         "liblog",
         "libnativehelper_compat_libc++",
     ],
+    static_libs: [
+        "libnetjniutils",
+    ],
 
     // We cannot use plain "libc++" here to link libc++ dynamically because it results in:
     //   java.lang.UnsatisfiedLinkError: dlopen failed: library "libc++_shared.so" not found

Tethering/jni/android_net_util_TetheringUtils.cpp

@@ -19,8 +19,8 @@
 #include <jni.h>
 #include <linux/filter.h>
 #include <nativehelper/JNIHelp.h>
-#include <nativehelper/JNIHelpCompat.h>
 #include <nativehelper/ScopedUtfChars.h>
+#include <netjniutils/netjniutils.h>
 #include <net/if.h>
 #include <netinet/ether.h>
 #include <netinet/ip6.h>
@@ -57,7 +57,7 @@ static void android_net_util_setupIcmpFilter(JNIEnv *env, jobject javaFd, uint32
         filter_code,
     };
 
-    int fd = jniGetFDFromFileDescriptor(env, javaFd);
+    int fd = netjniutils::GetNativeFileDescriptor(env, javaFd);
     if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)) != 0) {
         jniThrowExceptionFmt(env, "java/net/SocketException",
                 "setsockopt(SO_ATTACH_FILTER): %s", strerror(errno));
@@ -79,7 +79,7 @@ static void android_net_util_setupRaSocket(JNIEnv *env, jobject clazz, jobject j
 {
     static const int kLinkLocalHopLimit = 255;
 
-    int fd = jniGetFDFromFileDescriptor(env, javaFd);
+    int fd = netjniutils::GetNativeFileDescriptor(env, javaFd);
 
     // Set an ICMPv6 filter that only passes Router Solicitations.
     struct icmp6_filter rs_only;