add FreeTexImageData hook to help single-copy texturing in drivers
diff --git a/src/mesa/drivers/common/driverfuncs.c b/src/mesa/drivers/common/driverfuncs.c
index 7ab5f48..69cc919 100644
--- a/src/mesa/drivers/common/driverfuncs.c
+++ b/src/mesa/drivers/common/driverfuncs.c
@@ -103,6 +103,7 @@
    driver->NewTextureObject = _mesa_new_texture_object;
    driver->DeleteTexture = _mesa_delete_texture_object;
    driver->NewTextureImage = _mesa_new_texture_image;
+   driver->FreeTexImageData = _mesa_free_texture_image_data; 
    driver->IsTextureResident = NULL;
    driver->PrioritizeTexture = NULL;
    driver->ActiveTexture = NULL;