raco.compile: remove eliminate_common_subexpressions
raco.compile: remove eliminate_common_subexpressions

It's not been tested or used in >1year, and there's no reason to think
it still works. However, I separated this removal into a separate
patch so that we can revert it if necessary.

uwescience/raco,uwescience/raco,uwescience/raco,uwescience/raco,uwescience/raco