aux/trace: use private refcounts for samplerviews
this avoids having the driver bypass the samplerview wrapper and destroying the samplerview prematurely, e.g., spec@sgis_generate_mipmap@gen-texsubimage
this avoids having the driver bypass the samplerview wrapper and destroying the samplerview prematurely, e.g., spec@sgis_generate_mipmap@gen-texsubimage