• Update to version 2020.04, first release in many years (unfortunately, it was tagged just before the commit 06e4728 which fixed building with Python 3.x, point GH_TAGNAME to it instead of pulling a patch)
• Drop explicit python:build' from USES list, because waf' implies it
• Add missing USE_XORG and put `xorg' on USES list
• For the time being, don't force C++14 while C++11 is sufficient until the code really starts using new features (see GitHub commit a6bbc01)

PR: 246793
Submitted by: David Schlachter