Previously the shader associated with a batch was
assigned separately. This meant on occasion, the
incorrect shader was used with the Metal backend.
Updating the shader fetch to use the context bound
shader instead of the batch shader member as per
OpenGL/Vulkan backends.
Also include state change check to be consistent
with OpenGL.
Authored by Apple: Michael Parkin-White
Co-authored-by: Michael Parkin-White <mparkinwhite@apple.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/111112
ca527efb9f