vc_render segfaults on Apple Silicon

[csparker247]

vc_render non-deterministically segfaults on Apple Silicon devices. To consistently reproduce, try to default texture any segmentation:

vc_render -i Testing.volpkg -s local-reslice-particle-sim

My debugging thus far shows that this command segfaults in graph::CalculateNumVertsNode::compute() because the mesh_ pointer is NULL. I haven't determined why this is.

The error does not occur in Debug builds (at least I haven't had it happen yet), but does occur in Release and RelWithDebInfo builds. I have not been able to reproduce the issue at all on Apple Intel devices.

If you encounter this issue, try running your command again as the issue seems to be non-deterministic. If you find a command that consistently reproduces this issue, please let us know.

[csparker247]

This appears to be an issue with smgl and will be fixed in #58.