This script will download and build tcpdump binaries for armeabi & x86 Android Platform with latest NDK version(recommended) or define inside the script your custom NDK version
If somebody is not paranoid that much and just wants binaries which simply work there are compiled arm and x86 versions of tcpdump in release section.
You can also download working app with tcpdump support , nmap and many other tools from Google Play : https://play.google.com/store/apps/details?id=com.eakteam.networkmanager