Minimum OpenGL requirements

[FedericoCeratto]

Hello, on PinePhone (running Mobian, Phosh on Wayland) tigr crashes out with a rather opaque GLXBadFBConfig error.

glxinfo | grep -e "OpenGL version" -e "Core" -e "Compatible" returns OpenGL version string: 2.1 Mesa 22.3.6

Steps to reproduce with the tigr example:

cd example/demo
make demo
./demo

FWIW MESA_GL_VERSION_OVERRIDE=2.1 ./demo did not help.

Possibly related to https://github.com/erkkah/tigr/pull/13 https://github.com/erkkah/tigr/issues/12