st/mesa: don't update vertex elements when GL doesn't change them

st/mesa: don't update vertex elements when GL doesn't change them

We rely on mesa/main to tell us whether to update vertex elements.
This decreases overhead for obvious reasons.

The select/feedback code path doesn't use this, which is why you see
unconditional "ALL" in a few codepaths.

This sequence of GL calls doesn't update vertex elements if only
the pointer and stride vary:
    glVertexPointer()
    glDrawElements()
    glVertexPointer()
    glDrawElements()
    glVertexPointer()
    glDrawElements()

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13512>