svga: try to emit fewer buffer rebind commands

svga: try to emit fewer buffer rebind commands

If a consecutive sequence of drawing commands references the same
vertex/index buffers, there should be no need to rebind the surfaces
for the second and subsequent drawing commands.

Apps that use multiple display lists benefit from this since the vertex
data for several display lists is often stored in one buffer.

In the case of the legacy E&S Glaze demo, this reduces the size of our
command buffers from 91KB to 44KB.  One WSI Fusion trace shows a 33%
reduction in command buffer sizes.

Tested with full piglit run.

Reviewed-by: Charmaine Lee <charmainel@vmware.com>