intel/compiler: Report the number of non-spill/fill SEND messages

intel/compiler: Report the number of non-spill/fill SEND messages

This can be useful to measure whether memory access optimizations are
having the desired effect.  For example, we might see a reduction in
image loads/stores, or constant buffer loads.  We can already see this
in cycle estimates to some extent, but this is a more direct approach,
minus a lot of the noise of random scheduler shuffling.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>