Updated to build with newer Python (3.6.2) and P4Python (r17.1).
Added check for a known (common?) error building Python, a missing zlib package.
If the Python build fails and the build log contains "zlib not available", helpful
information on how to solve that problem is displayed (sudo yum install/
sudo apt-get install commands).
Added check for a known (common?) error building P4Python, a missing crypto package.
If the P4Python build fails and the build log contains "cannot find -lcrypto",
helpful information on how to solve that problem is displayed (sudo yum install/
sudo apt-get install commands).