Import Thomas Helstrom's SSE memcpy code from the via X.org driver.
Add a TextureMemCpy callback, called from texstore.c when copying
texture data via the memcpy_texture() path.
Enable this code in the via driver - 100% speedup in texdown.c results.
diff --git a/src/mesa/drivers/common/driverfuncs.c b/src/mesa/drivers/common/driverfuncs.c
index dcaaa91..4a8ea31 100644
--- a/src/mesa/drivers/common/driverfuncs.c
+++ b/src/mesa/drivers/common/driverfuncs.c
@@ -107,6 +107,7 @@
driver->DeleteTexture = _mesa_delete_texture_object;
driver->NewTextureImage = _mesa_new_texture_image;
driver->FreeTexImageData = _mesa_free_texture_image_data;
+ driver->TextureMemCpy = _mesa_memcpy;
driver->IsTextureResident = NULL;
driver->PrioritizeTexture = NULL;
driver->ActiveTexture = NULL;