svga: fix PIPE_TEXTURE_RECT/BUFFER const buffer issue

svga: fix PIPE_TEXTURE_RECT/BUFFER const buffer issue

The flag_rect and flag_buffer fields didn't sufficiently capture
the state changes needed for those resource types.  For example,
if a texture binding was changed from a 500x500 rect texture to a
400x400 rect texture we didn't set SVGA_NEW_TEXTURE_CONSTS.  But
we need to do that to emit the new texcoord scale factors to the
constant buffers.  Rather than track the sizes of all bound
resources, just set the flag if the resource is a rect.  Same
story with texture buffers.

Also, since rect/buffer textures are usable with VS/GS shaders,
add SVGA_NEW_TEXTURE_CONSTS to the flags we check for emitting
VS/GS constants.

This seems to help with XFCE / xfwm4 desktop scaling.
VMware issue 2156696.

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