Blender Git Loki

Mesh: Batch cache: Fix sculpt update issue.

Old solution was to create a new vbo and copy it to the location of
the old vbo hoping for the batches to update their vaos before drawing.

The issue is that the new VAO caching is not updating the VAOs at all
unless the shader interface changes.

So unless we expand gawain to support updating of vertex buffers (in a
better way than the current "dynamic" buffer) we need to delete every batch
linked to the vbo we want to recreate.

This solution might have performance implications.