shiny/driver/gldriver: disable forced OpenGL acceleration on macOS
shiny/driver/gldriver: disable forced OpenGL acceleration on macOS

Fixes golang/go#19191

Change-Id: I932119963f5ea46166d741c9427a6941ed700ee5
Reviewed-on: https://go-review.googlesource.com/44379
Reviewed-by: Nigel Tao <58ae08b3356928ff9c67562b4719487d54fe8348@golang.org>

golang/exp,golang/exp,golang/exp