anv: expose support for VK_KHR_sampler_mirror_clamp_to_edge
anv: expose support for VK_KHR_sampler_mirror_clamp_to_edge

This is already supported in genX_state.c, expose the extension string.

Signed-off-by: Ilia Mirkin <bcbbb7aa705ec3a5fc5824c01a845186c3d62fca@alum.mit.edu>
Reviewed-by: Jason Ekstrand <b186559eaedf698788888c8a2559b4efb4db10d6@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler