matloob: add a main file
matloob: add a main file

Tools are the best!

Change-Id: If0f3772def8f05c1c54957bef11ff01036783de4
Reviewed-on: https://go-review.googlesource.com/48789
Reviewed-by: Jessica Frazelle <b1c1d8736f20db3fb6c1c66bb1455ed43909f0d8@jessfraz.com>

golang/scratch