Action plan for 16.x upgrades

[AshCripps]

This issue is the tracker for the updates and upgrades we need to undertake before the release date of 16.x in April 2021.

Toolchain updates

These machines will need the new versions installed and added to the ansible scripts

• Linux x86
• Linux arm
• Linux cross compiling
• MacOS
• Windows
• AIX
• zLinux
• Linux on P
• IBMi
• zOS
• smartos

Scripts

• Select-Compiler
• Possible some other jenkins scripts?

Known Issues/Blockers