graphics/qgis: Update to 3.16.0

This update from 3.14.16 to 3.16.0 fixes many bugs and brings a lot of new features[1].

• Ability to export temporal animation frames
• Added a new goto locator filter
• Add context menu to map canvas
• Many styling and labelling improvements
• Render axis for stacked bar diagram
• Many mesh datasets and layer improvements
• New features in rendering and 3D
• better print layout
• New features in expressions and digitizing
• ...

[1] https://qgis.org/en/site/forusers/visualchangelog316/index.html

The port now integrates OpenCL functionality.

Reviewed by: arrowd (mentor)
Differential Revision: https://reviews.freebsd.org/D26951