runtime: get rid of goalg, no longer needed

The goalg function was a holdover from when we had algorithm
tables in both C and Go.  It is no longer needed.

Change-Id: Ia0c1af35bef3497a899f22084a1a7b42daae72a0
Reviewed-on: https://go-review.googlesource.com/2099
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>