i965: dump scheduling cycle estimates

i965: dump scheduling cycle estimates

The heuristic we're using is rather lame, since it assumes everything is
non-uniform and loops execute 10 times, but it should be enough for
measuring improvements in the scheduler that don't result in a change in
the number of instructions.

v2:
- Switch loops and cycle counts to be compatible with older shader-db.
- Make loop heuristic 10x to match with spilling code.

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>