@tom666
Thanks for the info. I was going to install then update WinAVR, but the installation wanted to muck with my path, I decided I did not trust it. Instead, I have an Ubuntu 16.04 installation running in a virtual machine, and was able to install gcc-avr and avr-libc. This works fine, and I don't need to corrupt my Windows 10.
By the way, my tester uses an ATMEGA328P, and even though the gcc-avr installed was 4.9.2, everything built fine and fit inside the part.
Bill