I downloaded the win2012 vigrant box and was able to build packetbeat on it by adding WpdPack 4.1.2 to c:\wpdpack\lib
I compared the setup from the vigrant box to my windows 10 setup and noticed that there was an additional environment variable set:
GO15VENDOREXPERIMENT=1
With this variable set I am able to build packetbeat on my windows 10
this enables go to use the go files from the vendor directory.