Add SOCK_CLOEXEC to NetlinkUtils.netlinkSocketForProto

Bug: 320420453

Test: atest NetworkStaticLibTests:com.android.net.moduletests.util.netlink.NetlinkUtilsTest

Change-Id: I166a0d5185a18274ed82f739f289969c1f989b20

staticlibs/device/com/android/net/module/util/netlink/NetlinkUtils.java

@@ -229,7 +229,7 @@ public class NetlinkUtils {
      * @throws ErrnoException if the FileDescriptor not connect to be created successfully
      */
     public static FileDescriptor netlinkSocketForProto(int nlProto) throws ErrnoException {
-        final FileDescriptor fd = Os.socket(AF_NETLINK, SOCK_DGRAM, nlProto);
+        final FileDescriptor fd = Os.socket(AF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, nlProto);
         Os.setsockoptInt(fd, SOL_SOCKET, SO_RCVBUF, SOCKET_RECV_BUFSIZE);
         return fd;
     }