update build script

scripts/build_upf.sh

@@ -12,6 +12,7 @@ N4PATH="$base/install/n4"
 
 
 function pre_install(){
+  sudo apt-get install ethtool	
   sudo apt-get install make
   sudo apt-get install cmake
   sudo apt-get install ccache
@@ -27,7 +28,7 @@ function vpp(){
    echo  "build vpp success"
    cp $base/src/vppe/build-root/install-vpp_debug-native/vpp/bin/* /usr/bin
    cp -r $base/src/vppe/build-root/install-vpp_debug-native/vpp/lib/vpp_plugins /usr/lib/x86_64-linux-gnu
-
+   groupadd  -g 344  vpp
    return  0
 
 }