requested to merge gerddie/virglrenderer:vrend-more-barries-and-vs-layers into master
- Check for GL_AMD_vertex_shader_layer which can be used to enable more cases where copies between PBOs and textures are done on the graphics card.
- Emitting GL_BUFFER_UPDATE_BARRIER_BIT and GL_TEXTURE_UPDATE_BARRIER_BIT when needed
- Prepare host for handling SSBO binding offsets that are needed when more than one shader stage uses SSBOs
Guest side changes are here: mesa/mesa!21586 (merged)